At any time after the principal money has become ⁹[due], the mortgagor has a right, on payment or tender, at a proper time and place, of the mortgage-money, to require the mortgagee (a) to deliver ¹⁰[to the mortgagor the mortgage-deed and all documents relating to the mortgaged property which are in the possession or power of the mortgagee], (b) where the mortgagee is in possession of the mortgaged property, to deliver possession thereof to the mortgagor, and (c) at the cost of the mortgagor either to re-transfer the mortgaged property to him or to such third person as he may direct, or to execute and (where the mortgage has been effected by a registered instrument) to have registered an acknowledgement in writing that any right in derogation of his interest transferred to the mortgagee has been extinguished:

Provided that the right conferred by this section has not been extinguished by act of the parties or by ¹¹[decree] of a Court. The right conferred by this section is called a right to redeem and a suit to enforce it is called a suit for redemption. Nothing in this section shall be deemed to render invalid any provision to the effect that, if the time fixed for payment of the principal money has been allowed to pass or no such time has been fixed, the mortgagee shall be entitled to reasonable notice before payment or tender of such money.

Redemption of portion of mortgaged property.—Nothing in this section shall entitle a person interested in a share only of the mortgaged property to redeem his own share only, on payment of a proportionate part of the amount remaining due on the mortgage, except ¹[only] where a mortgagee, or, if there are more mortgagees than one, all such mortgagees, has or have acquired, in whole or in part, the share of a mortgager.