and Telangana Industrial Infrastructure Ltd., are estopped from challenging the validity of the mortgage.” In State of Haryana v Narvir Singh, (2014) 1 SCC 105, this Court observed: “11. A mortgage inter alia means transfer of interest in the specific immovable property for the purpose of securing the money advanced by way of loan. Section 17(1)(c) of the Registration Act provides that a non- testamentary instrument which acknowledges the receipt or payment of any consideration on account of the creation, declaration, assignment, limitation or extension of any such right, title or interest, requires compulsory registration. A mortgage by deposit of title deeds in terms of Section 58(f) of the Transfer of Property Act surely acknowledges the receipt and transfer of interest and, therefore, one may contend that its registration is compulsory. However, Section 59 of the Transfer of Property Act mandates that every mortgage other than a mortgage by deposit of title deeds can be effected