<PAGE>
 
                                                                   EXHIBIT 10(M)

                         [LOGO OF ICIFC APPEARS HERE]
                        
                            ICI FUNDING CORPORATION     
                            -----------------------       
            A SUBSIDIARY OF IMPERIAL CREDIT MORTGAGE HOLDINGS, INC.

                                                           Commitment No. MA3665
                                                            Seller No. 000600013


September 12, 1997


Mr. Russ Kidder
Managing Director
EMB MORTGAGE CORPORATION
575 Anton Blvd., Suite 200
Costa Mesa, CA 92626

RE:  MASTER COMMITMENT TO PURCHASE SECOND TRUST DEED MORTGAGE LOANS UNDER
     PROGRESSIVE EQUITY EXPRESS PROGRAM

Dear Mr. Kidder:

ICI FUNDING CORPORATION, an indirect subsidiary of IMPERIAL CREDIT MORTGAGE
HOLDINGS, INC., hereinafter referred to as "Buyer," hereby commits to
purchase/fund from EMBl MORTGAGE CORPORATION, hereinafter referred to as
"Seller," second trust deed mortgage loans ("Mortgage Loans") pursuant to the
terms and conditions set forth herein. By executing this master commitment (the
"Commitment"), Buyer hereby agrees to purchase, and Seller hereby agrees to sell
those certain Mortgage Loans, subject to the terms and conditions hereof.

     1.   AMOUNT OF COMMITMENT: The amount of the commitment is $25,000,000.
          --------------------                                              

     2.   TERM OF COMMITMENT: The term of this Commitment is six (6) months. The
          -------------------
          Commitment expiration date will be March 15. 1998, or upon the
          fulfillment of the amount of the Commitment whichever occurs first.
          All Mortgage Loans must be committed and delivered to Buyer in
          purchasable form prior to the expiration of this Commitment, in order
          for Buyer to purchase under the terms of this Commitment.

     3.   LOAN PROGRAM: All Mortgage Loans purchased under this Commitment shall
          ------------                                                          
          conform to the requirements and the underwriting guidelines of the
          Progressive Express Equity Plus program (the "Program"), as set forth
          in ICI Funding Corporations' Sellers Guide, dated June, 1997, as
          modified per this Commitment (the "Guide"). Seller acknowledges that
          it has received a copy of the Guide and is familiar with the
          requirements thereof including the Program. All Mortgage Loans sold to
          Buyer will conform to the requirements and underwriting guidelines of
          the Program. All fundings under this Commitment shall be governed by
          the terms hereof, together with the Guide and the "Seller Agreement"
          attached hereto as Exhibit "A" all of which are collectively referred
          to herein as the "Purchase Documents."

                                       1
<PAGE>
 
     4.   PURCHASE PRICE: The purchase price will be based on rates and prices
          --------------                                                      
          provided on a daily basis by Buyer via facsimile transmission no later
          than 7:30 am. (PST).

     5.   COMMITMENT FEE: An up front commitment fee of one-eighth of one
          -------------- 
          percent (.125%) will be waived by Buyer in exchange for 15,000 shares
          of Seller's non-restricted stock at a price of $2.00 (assuming the
          stock currently trades at $4.00).

     6.   ELIGIBLE PRODUCT TYPES: Second trust deed mortgage loans conforming to
          ----------------------                         
          the Program. A copy of the Program guidelines is attached hereto as
          Exhibit "B."

     7.   UNDERWRITING GUIDELINES: All loan documentation and underwriting must
          -----------------------                    
          be in compliance with the Purchase Documents as the same may be
          modified hereby the Delivery Percentage Limitations set forth on
          Exhibit "C" attached hereto. Additional exceptions to the Purchase
          Documents must be approved by Buyer prior to the delivery of the loan
          for purchase. Program parameters and pricing parameters are subject to
          change upon delivery of thirty (30) days prior written notice by Buyer
          to Seller.

     8.   DELEGATED UNDERWRITING: Seller has delegated underwriting on
          ----------------------
          Progressive Express Equity Plus program subject to mandatory training
          and a complete underwriting and legal review by an acceptable ICIFC
          Contract Service on each loan prior to the delivery for purchase.
          Buyer will have the right to terminate all or any portion of the
          delegation given to the Seller providing Buyer notify Seller in
          writing stating a termination date of such delegation. All costs for
          contract services will be the responsibility of the Seller.

     9.   ADMINISTRATION FEE: $125.00 per loan.
          ------------------                   

     10.  LOCK-IN PROCEDURES: Seller will reference this Commitment number and
          ------------------  
          specify the preferred pricing parameters at time of commitment, and
          follow the standard requirements of the Guide for best efforts lock-
          in. Bulk lock-ins are allowed for a minimum of $500,000 and are
          considered mandatory delivery, plus or minus two percent (2%).

     11.  SERVICING: Loans shall be sold in their entirety to Buyer, with
          ---------               
          servicing rights of such loans released to Buyer upon purchase. All
          servicing rights of loans purchased according to this Commitment shall
          be included with this purchase and shall be considered transferred and
          owned by Buyer as of the date of funding of each loan purchase and
          Seller shall have no further rights or claims of any type as of the
          date of each loan purchase.

          All servicing activities, records, funds and including, but not
          limited to, any escrow and buydown balances, all funds held for the
          benefit of these loans, and insurance records shall be transferred to
          Buyer on the date of purchase. The cost for establishing new tax
          service contracts will be at Seller's expense.

     12.  PAIR-OFF: Once Mortgage Loans are locked in for block commitments, a
          --------
          pair-off fee equal to any market movement, will be assessed on the
          difference, if any, between the

                                       2
<PAGE>
 
          commitment amount (minus delivery tolerance) and the actual amount
          delivered. Seller will remit payment to Buyer for the amount of the
          pair-off fee within ten (10) days from the expiration date of the
          block commitment.

     13.  SALES AND FUNDING: Seller's warehouse line will be swept by Buyer on
          -----------------
          the last day of each month or at Seller's request. Funding will occur
          within seventy-two (72) hours of delivery, provided Seller delivers
          all required documents and fulfills all outstanding conditions under
          the Purchase Documents, including, without limitation, the delivery to
          Buyer of (a) a computer tape presenting Mortgage Loans completed with
          data fields audited and re-verified to each loan file. (b) the
          original promissory notes evidencing the Mortgage Loans to be
          purchased, duly endorsed in favor of Buyer, prior to the purchase
          date, and (c) copies of the assignment of deed of trust or mortgage
          (in addition to other documents outlined in the Guide).

     14.  INDEMNIFICATION: Without limiting any of Buyer's rights contained in
          ---------------               
          this Commitment, Seller shall indemnify, defend and hold Buyer, its
          successors and assigns, and its officers, agents, and employees
          harmless from and against all claims, legal or arbitration
          proceedings, loss, liability, damages, fees and costs (including,
          without limitation, actual credit reporting agency costs, and
          attorneys' fees and costs), which arise from or are related to,
          directly or indirectly, (a) the failure of any Mortgage Loan to comply
          with the underwriting criteria or any of the other requirements of the
          Purchase Documents, including, without limitation the Guide, or (b)
          Seller's breach of any warranty, representation, or covenant contained
          in the Purchase Documents. This remedy is cumulative, and shall be in
          addition to all other rights and remedies afforded Buyer hereunder,
          under the Purchase Documents, at law or in equity.

     15.  MODIFICATION, AMENDMENT AND WAIVER: No modification or waiver of or
          ----------------------------------               
          amendment to any of the terms of this Commitment shall be effective
          unless it is in writing signed by all parties hereto. No waiver of any
          default or breach by Seller shall be implied from any omission by
          Buyer or its assigns to take any action on account of such default if
          such default continues or is repeated. No written waiver shall affect
          any breach other than the breach specified in such waiver, and then
          only to the extent therein expressly stated. Any failure or delay by
          Buyer or its assigns in exercising any rights, power, or remedy
          hereunder shall not be deemed a waiver thereof,

     16.  ASSIGNMENT: This Commitment is only assignable by Buyer. This
          ----------
          Commitment is not intended to benefit any third party. Buyer may only
          assign this Commitment to a party who has the ability to perform all
          of Buyer's obligations under this Commitment.

     17.  APPLICABLE LAW/VENUE/ARBITRATION: The Commitment shall be governed by
          --------------------------------
          and construed under the laws of the State of California. Any
          controversy, claim or dispute among the parties arising out of this
          contract, or the breach thereof, shall be settled by arbitration in
          accordance with the Commercial Arbitration Rules of the American
          Arbitration Association in Orange County, California and judgment upon
          the award rendered by the Arbitrator may be entered in any court
          having jurisdiction, including the Superior Court of California,
          County of Orange.

                                       3
<PAGE>
 
     18.  ENFORCEMENT: In the event of any action by Buyer or Seller to enforce
          ----------- 
          this Commitment, the prevailing party shall be entitled to receive, in
          addition to all other relief, the costs thereof including, without
          limitation, attorney's fees and court costs.

     19.  ENTIRE AGREEMENT: This Commitment and any agreement, document or
          ---------------- 
          instrument attached hereto or referenced herein integrates all of the
          terms and conditions mentioned herein or incidental hereto, and
          supersedes all oral negotiations and prior writings regarding the
          subject matter hereof

     20.  FURTHER ACTS: Buyer and Seller mutually agree that each of them will
          ------------                                                        
          immediately upon demand by the other party, execute such documents or
          perform such acts as may reasonably be required by such party to
          perform their objectives under this agreement; and refusal to
          cooperate and execute such documents or perform such acts required by
          this agreement shall be considered a material breach hereof and shall
          suspend the performance of non-breaching party.

     21.  SURVIVAL: All representations and warranties within the Purchase
          --------    
          Documents shall survive the transfer of Mortgage Loans to and purchase
          by Buyer, its successors and assigns.

     22.  NOTICES: All notices, requests, demands or other communications that
          -------
          are to be given under this contract shall be in writing, addressed to
          the appropriate parties and sent postage prepaid to the address below:

                    If to Buyer:   ICI Funding Corporation
                                   20371 Irvine Ave., Bldg. A
                                   Santa Ana Heights, CA 92707
                                   ATTN:  Mary Glass-Schannault

                    If to Seller:  EMB MORTGAGE CORPORATION
                                   575 Anton Blvd., Suite 200
                                   Costa Mesa, CA 92626
                                   ATTN:  Russ Kidder

     23.  SEVERABILITY: Whenever possible, each provision of this Commitment
          ------------     
          shall be interpreted in such manner as to be valid and effective under
          applicable law, but if any such provision shall be ineffective to the
          extent of such prohibition or invalidity without invalidating the
          remainder of such provision or the remaining provisions of the
          Commitment.

     24.  HEADINGS: The headings used herein are used for convenience only, are
          --------
          not part hereof and shall not be used in construing this Commitment.

     25.  COUNTERPARTS: This Commitment may be executed in any number of
          ------------     
          counterparts and all such counterparts taken together shall be deemed
          to constitute one and the same instrument.

                                       4
<PAGE>
 
     26.  FINANCIAL CONDITION: Prior to, or concurrent with the execution of
          -------------------
          this Commitment, Seller agrees to submit a recent audited financial
          statement. Unless otherwise waived by Buyer, Seller must have and
          maintain a minimum audited net worth of at least $2,000,000 in order
          for Buyer to purchase Mortgage Loans under this Commitment.


If the terms and conditions of the Commitment are acceptable to Seller, please
execute the acceptance where indicated on this Commitment and return one copy of
the signed agreement. A signed copy hereof signed by Seller must be received by
Buyer or its authorized representative within five (5) business days of receipt
by Seller, or this agreement will be considered null and void.

The individuals executing this Commitment by their signatures do hereby certify
they are duly authorized to execute this document on behalf of the parties they
represent.

     "BUYER"

     ICI FUNDING CORPORATION

     By:/s/ Mary Glass-Schannault
        ------------------------------
         Name: Mary Glass-Schannault
         Title: Senior Vice President 

     By:______________________________
         Name:  James W. Dickinson
         Title:  Vice President


We hereby acknowledge and accept all of the terms and conditions of this
Commitment for the sale of the Mortgage Loans described herein:


     "SELLER."

     EMB MORTGAGE CORPORATION

     By /s/ Russ Kidder  
        -------------------------------
         Name: Russ kidder
         Title: Managing Director

                                       5
<PAGE>
 
                                  EXHIBIT "B"

                COPY OF PROGRESSIVE EXPRESS EQUITY PLUS PROGRAM

<PAGE>
 
                                   EXHIBIT C

                        DELIVERY PERCENTAGE LIMITATIONS
                        -------------------------------


     The purchased Mortgage Loans will be subject to the following limitations:

     (a)  Weighted Average Coupon: Subject to the eligible loan product types,
          the minimum gross weighted average coupon for the Commitment will be
          14%, unless Seller is otherwise notified by Buyer.

     (b)  Reduced Documentation: Reduced documentation Mortgage Loans not to
          exceed 40% of the aggregate amount of all Mortgage Loans delivered
          pursuant to the Commitment.

     (c)  Geographic Limitation: United States. Not more than 50% of the
          Commitment may consist of Mortgage Loans located in California. As set
          forth in the Progressive Express Equity Plus Parameters, no Mortgage
          Loans will be accepted from Alabama, Alaska, Texas, Hawaii or the
          United States Territory of Puerto Rico.

     (d)  CLTV Limitations: The aggregate amount of all Mortgage Loans delivered
          pursuant to the Commitment shall have a weighted combined loan to
          value of greater than [115%].

     (e)  Debt Consolidation Percentage: Seventy percent (70%) of the aggregate
          amount of all Mortgage Loans delivered pursuant to the Commitment
          shall be debt consolidation loans payable through the closing agent.

     (f)  The aggregate amount of all Mortgage Loans delivered pursuant to the
          Commitment shall have a 680 FICO score weighted average.

     (g)  Loans made to Condominium Properties are limited to 20% of the total
          Commitment.

     (h)  Loans made to Unit Properties are limited to 20% of the total    
          Commitment.