21 Pa. Stat. § 735
Any owner of real estate who shall have given his bond or other obligation, secured by mortgage upon his real estate or any part thereof, and who shall afterwards have granted and conveyed the mortgaged premises to another, subject to the said mortgage, whether mentioned in the said conveyance or not, or leaving the said bond or other obligation and mortgage outstanding, shall have the right at any time after the maturity of the said bond or other obligation and mortgage, according to the terms and conditions thereof, to tender to the mortgagee or other owner or holder, at that time, of the said bond or other obligation and mortgage, and make payment of the mortgage debt and interest to date of tender, including cost if any; and, if entitled in equity to be subrogated to the rights of the holder of the bond and mortgage against the vendees or their heirs or assigns, owners of the lands, thereupon to demand and require the said mortgagee, or other owner or holder thereof, to assign and transfer the said bond or other obligation and mortgage to him, the mortgagor, or his nominee, at the proper cost and expense of the said mortgagor; and if the said mortgagee, or other owner or holder of the said bond or other obligation and mortgage, shall fail or neglect to so assign and transfer the said bond or other obligation and mortgage, upon such tender of payment to him or them, together with any judgment or judgments entered thereon, the interest on the mortgage debt shall cease to run on the said indebtedness, as against the mortgagor, from the date of such tender, and he shall not be liable for any costs, charges, commissions or expense accruing after the date of such tender.
21 P.S. § 735