Reference for Gittin 68:9
<big><strong>גמ׳</strong></big> מאי איריא אלמנה אפילו כולי עלמא נמי דהא קיימא לן הבא ליפרע מנכסי יתומין לא יפרע אלא בשבועה אלמנה אצטריכא ליה סד"א
RABBAN GAMALIEL THE ELDER THEREUPON MADE A REGULATION THAT SHE SHOULD TAKE ANY VOW<span class="x" onmousemove="('comment',' E.g., a vow to abstain from certain kinds of food if it should be found that she had already received any part of the kethubah. ');"><sup>16</sup></span> WHICH THE ORPHANS CHOSE TO IMPOSE ON HER AND SO RECOVER HER <i>KETHUBAH</i>. AND [SIMILARLY] WITNESSES SIGN THEIR NAMES TO A GET TO PREVENT ABUSES.<span class="x" onmousemove="('comment',' V. infra. Lit., 'for the better ordering of society.' ');"><sup>17</sup></span> HILLEL THE ELDER ALSO INSTITUTED THE <i>PROSBUL</i><span class="x" onmousemove="('comment',' V. Glos. and infra. ');"><sup>18</sup></span> TO PREVENT ABUSES. <b><i>GEMARA</i></b>. Why is this rule [about an oath] laid down with reference to a widow, seeing that it applies to everybody, since it is an established rule that 'one who seeks to recover payment from the property of orphans<span class="x" onmousemove="('comment',' For a debt incurred by their father. ');"><sup>19</sup></span> cannot recover save on taking an oath'?<span class="x" onmousemove="('comment',' B.B. 5b; Keth. 872. ');"><sup>20</sup></span> — There is a special reason for the mention of a widow. For it might occur to you to say that