NY CPLR § 4519 (2021)
2021 New York Laws CVP - Civil Practice Law and Rules Article 45 - Evidence 4519 - Personal Transaction or Communication Between Witness and Decedent or Person With a Mental Illness.

§  4519.  Personal  transaction  or  communication between witness and   decedent or person with a mental illness. Upon the trial of an action or   the hearing upon the merits of a special proceeding, a party or a person   interested in the event, or a person from, through or under whom such  a   party  or  interested person derives his interest or title by assignment   or otherwise, shall not be examined as a witness in his  own  behalf  or   interest,  or in behalf of the party succeeding to his title or interest   against the executor, administrator or survivor of a deceased person  or   the  committee  of  a person with a mental illness, or a person deriving   his title or interest from, through or under a deceased person or person   with a mental illness, by assignment or otherwise, concerning a personal   transaction or communication between the witness and the deceased person   or  person  with  a  mental  illness,   except   where   the   executor,   administrator,  survivor,  committee  or  person  so  deriving  title or   interest is examined in his own behalf, or the testimony of  the  person   with  a  mental  illness  or  deceased  person  is  given  in  evidence,   concerning the same transaction or communication. A person shall not  be   deemed  interested for the purposes of this section by reason of being a   stockholder or officer of any banking corporation which is  a  party  to   the  action  or proceeding, or interested in the event thereof. No party   or person interested  in  the  event,  who  is  otherwise  competent  to   testify,   shall   be  disqualified  from  testifying  by  the  possible   imposition of costs against him or the award of costs to him. A party or   person interested in the event or a person from, through or  under  whom   such  a  party  or  interested  person  derives his interest or title by   assignment or otherwise, shall not be qualified for the purposes of this   section, to testify in his own behalf or interest, or in behalf  of  the   party  succeeding  to his title or interest, to personal transactions or   communications with the donee of a power of appointment in an action  or   proceeding  for  the  probate  of a will, which exercises or attempts to   exercise a power of appointment granted by the will of a donor  of  such   power,  or  in an action or proceeding involving the construction of the   will of the donee after its admission to probate.Nothing contained in this section,  however,  shall  render  a  person   incompetent  to  testify  as  to the facts of an accident or the results   therefrom where the proceeding, hearing,  defense  or  cause  of  action   involves  a  claim of negligence or contributory negligence in an action   wherein one or more parties is  the  representative  of  a  deceased  or   incompetent  person  based  upon,  or  by  reason  of,  the operation or   ownership of a motor vehicle being operated upon  the  highways  of  the   state,  or  the operation or ownership of aircraft being operated in the   air space over the state, or the operation or ownership of a  vessel  on   any of the lakes, rivers, streams, canals or other waters of this state,   but  this provision shall not be construed as permitting testimony as to   conversations with the deceased.