66. It shall be competent for the Certificate Officer in executing any certificate or decree under this Chapter to order the payment of the amount of such certificate or decree to be made by the certificate or judgment-debtor by instalments within a period not exceeding three years from the date of such order and to stay the execution of the certificate or decree for such period: Provided that in default of payment of any instalment, the certificate or decree may be executed for the whole of the outstanding balance thereof.