Mistake referred to in Proviso (1) to Section 92 of Indian Evidence Act, refers to

Section 92 reads as - Exclusion of evidence of oral agreement. –– When the terms of any such contract, grant or other disposition of property, or any matter required by law to be reduced to the form of a document, have been proved according to the last section, no evidence of any oral agreement or statement shall be admitted, as between the parties to any such instrument or their representatives in interest, for the purpose of contradicting, varying, adding to, or subtracting from, its terms. Proviso (1) to Section 92 states that if the terms of any such contract have been reduced to the form of a document which has been executed by any or all of the parties, then no evidence shall be given in proof of the terms of any oral agreement or statement made prior to the execution of the document, except in cases of fraud, mistake, or misrepresentation. Thus, the proviso to Section 92 allows evidence of oral agreement or statement to be admitted in court in case of mistake. The mistake referred to in this proviso can be either unilateral or mutual.