Explanation:

Section 26 of Specific Relief Act – 
26. When instrument may be rectified.—(1) When, through fraud or a mutual mistake of the parties a contract or other instrument in writing [not being the articles of association of a company to which the Companies Act, 1956 (1 of 1956), applies] does not express their real intention, then— (a) either party or his representative in interest may institute a suit to have the instrument rectified; or (b) the plaintiff may, in any suit in which any right arising under the instrument is in issue, claim in his pleading that the instrument be rectified; or (c) a defendant in any such suit as is referred to in clause (b), may, in addition to any other defence open to him, ask for rectification of the instrument.