(2) No order directing the tenant to deliver possession of the building under this section shall be passed (a) on the ground specified in clause (a) of subsection (1), unless the landlord gives an undertaking that the building shall, on completion of the repairs, be offered to the tenant, who delivered possession in pursuance of an order under sub section (1) for his re occupation before the expiry of three months from the date of recovery of possession by the landlord, or before the expiry of such further period as the Controller may, for reasons to be recorded in writing, allow; or 9 (b) on the ground specified in clause (b) of subsection (1), unless the landlord gives an undertaking that the work of demolishing any material portion of the building shall be substantially commenced by him not later than one month and shall be completed before the expiry of three months from the date he recovers possession of the entire building or before the expiry of such further period as the Controller may, for reasons to be recorded in writing, allow.