Reference for Gittin 115:22
לקח מן הסיקריקון וכו': אמר רב לא שנו אלא דאמר לו לך חזק וקני אבל בשטר קנה ושמואל אמר אף בשטר נמי לא קנה עד שיכתוב לו אחריות
IF A MAN BUYS FROM THE SICARICON etc. Rab said: This holds good only where he [the original owner] said to him<span class="x" onmousemove="('comment',' To the buyer. ');"><sup>18</sup></span> [mere ly]: Go, take possession<span class="x" onmousemove="('comment',' By doing a little work on the property. ');"><sup>19</sup></span> and acquire ownership. If, however, he gave him a written deed, he does acquire title. Samuel said: Even with a written deed he does not acquire title, unless he expressly makes himself responsible.<span class="x" onmousemove="('comment',' For reimbursing him if his title should prove invalid. ');"><sup>20</sup></span>