New York Consolidated Laws, General Obligations Law - GOB § 17-105. Promises and waivers affecting the time limited for action to foreclose a mortgage

2. a. A statement by a grantee of real property or assignee of a lease of real property, effective under section 5-705 of this chapter as an assumption of or agreement to pay an indebtedness or other sum secured by a mortgage of such property or lease has also, to the extent of the amount specified therein, the same effect as provided in this section with respect to a waiver or promise described in subdivision one, unless it contains language disclaiming an intention to affect the statute of limitation.

b. A recital, in an instrument in which real property is conveyed or a lease is assigned, that the conveyance or assignment is made subject to a mortgage, or provision to that effect in a contract for purchase of real property or purchase of a lease, or an agreement or instrument by which another encumbrance or interest is subordinated to the lien of a mortgage, does not have the effect provided in this section with respect to a waiver or promise described in subdivision one.

a. against (1) the person who made it, to the extent of any interest held by him at the date thereof and (2) any person subsequently acquiring from him any such interest, without giving value or with actual notice of the making of the waiver or promise, to the extent of the interest so acquired;  and

b. in favor of (1) the mortgagee or his assignee, (2) any other person to whom or for whose benefit it is expressed to be made, and (3) any person who, after the making of the waiver or promise, succeeds or is subrogated to the interest of either of them in the mortgage or otherwise acquires an interest in the enforcement of the mortgage.

a. a payment or part payment of the principal or interest secured by the mortgage, or

b. a stipulation made in an action or proceeding.