Section 70(1)(b) in The Mumbai Municipal Corporation Act, 1888
(b)every contract for the execution of any work or the supply of any materials or goods which will involve an expenditure exceeding [fifty thousand rupees] [These words were substituted for the words 'ten thousand rupees' by Maharashtra 10 of 1998, Section 33(a).] shall be in writing and shall be sealed with the common seal of the corporation [in the manner prescribed in sub-section (2)] [These words, brackets, and figure were inserted by Bombay 10 of 1935, Section 2(1).] and shall specify the work to be done or the materials or goods to be supplied, as the case may be, the price to be paid for such work, materials or goods, and, in the case of a contract for work, the time or times within which the same or specified portions thereof shall be completed.