N.Y. Real Prop. Acts. Law § 254-a

§ 254-a. Right of election of mortgagee in certain cases. If a bond or\nnote, or the mortgage on real property, improved by a one to six family\nresidence occupied by the owner, securing the payment of same, contains\n(1) a provision whereby the mortgagee retains the right to accelerate\nthe due date for payment of the balance of principal upon a transfer or\nsale of such real property or by alienation of title of such real\nproperty due to an act or operation of law, and (2) a provision for\npayment of any charge, however denominated, in the nature of a\nprepayment fee and if a mortgagor sells or transfers his property or if\ntitle to the mortgaged property is transferred by act or operation of\nlaw and the purchaser requests permission to assume the mortgage or take\nthe mortgaged premises subject to the mortgage, but the mortgagee does\nnot consent to such request and thereby necessitates prepayment of the\nmortgage, the mortgagee shall not levy a prepayment fee; provided,\nhowever, that the provisions of this section shall not apply to the\nextent such provisions are inconsistent with any federal law or\nregulation.\n