Reference for Bava Batra 308:9
אמר ליה אי עדים אלימי ומרעי שטרא איהו כל כמיניה אמר ליה והלא משמך אמרו יפה ערערו בני משפחה אמר ליה זו אלעזר אמרה אני לא אמרתי דבר זה מעולם
[that where] one admitted that he wrote a deed no attestation is required. But, surely, [Resh Lakish rejoined,] they<span class="x" onmousemove="('comment',' R. Meir and the Sages. ');"><sup>30</sup></span> are actually in dispute [on this question]; as it was taught, 'They are not believed [so far as] to invalidate it; these are the words of R. Meir. But the Sages say: They are believed'!<span class="x" onmousemove="('comment',' Keth. 18b. Cf. supra 154a, q.v. for notes. ');"><sup>31</sup></span> — He replied to him: [Should] he, because<span class="x" onmousemove="('comment',' Lit., 'if'. ');"><sup>32</sup></span> witnesses are all-powerful and [may] impair [the validity of] a deed,<span class="x" onmousemove="('comment',' Witnesses, according to the Sages. are justly entitled to invalidate a deed, despite the debtor's admission that he wrote it. ');"><sup>33</sup></span>