Reference for Bava Batra 339:12
והוינן בה ולית ליה לרבי הא דתנן שנים אוחזין בטלית זה אומר אני מצאתיה וזה אומר אני מצאתיה זה ישבע שאין לו בה פחות מחציה וזה ישבע שאין לו בה פחות מחציה ויחלוקו
admitted that he wrote a deed,<span class="x" onmousemove="('comment',' And he only disputes its validity. In the case under discussion, e.g., he might plead that he did not deliver the deed to the other party, as the sale never took place, but he lost the document and the other found it. ');"><sup>22</sup></span> [independent legal] attestation is required. For Rabbi holds [that where a person] admitted that he wrote a deed, no [independent] attestation is required;<span class="x" onmousemove="('comment',' Consequently, in the present case since the seller admits the writing of the deed and only disputes the buyer's claim, the latter's word is accepted and there is no need to hear witnesses on the question of undisturbed possession. ');"><sup>23</sup></span>