Reference for Bava Batra 70:6
דאי לא תימא הכי הני משכנתא דסורא דכתב בהו במשלם שניא אלין תיפוק ארעא דא בלא כסף אי כביש ליה לשטר משכנתא גביה ואמר לקוחה היא בידי הכי נמי דמהימן מתקני רבנן מידי דאתי ביה לידי פסידא אלא איבעי ליה למחויי הכא נמי איבעי ליה למחויי
He said: He should have lodged a protest within three years. For, were you not to say so, then what about the so-called 'mortgage of Sura'<span class="x" onmousemove="('comment',' A form of deed by which a borrower transferred property to the lender for a fixed number of years. ');"><sup>10</sup></span> containing the stipulation, 'On the termination of these [X] years this land shall be given up without payment.' Now suppose the mortgagee suppresses the mortgage bond and asserts that he has bought the land; are we indeed to say that his plea is to be accepted? Would the Rabbis make a regulation<span class="x" onmousemove="('comment',' Viz., that three years' occupation gives a title to ownership. ');"><sup>11</sup></span>