Transfer of Property Act, 1882
59. Mortgage when to be by assurance
Where the principal money secured is one hundred rupees or upwards, a mortgage other than a mortgage by deposit of title deeds can be effected only by a registered instrument signed by the mortgagor and attested by at least two witnesses.
Where the principal money secured is less than one hundred rupees, a mortgage may be effected either by a registered instrument signed and attested as aforesaid or (except in the case of a simple mortgage) by delivery of the property.