Halakhah for Bava Kamma 205:3
ואם אמר לו על מנת כופין את המוכר למכור פשיטא לא צריכא דאמר להו לסהדי קמיה דידיה חזו דשטרא אחרינא קא בעינא מהו דתימא מצי א"ל אמינא שטרא מהיאך דקא שקלת בשמיה קאמרת קא משמע לן דאמר ליה להכי טרחי ואמרי להו לעדים קמך דמינך הוא דקא בעינא
[But what comparison is there?] Had R. Kahana given four to receive eight [so that it were usury]? Was it not his flax<span class="x" onmousemove="('comment',' After it had legally been transferred to him. ');"><sup>7</sup></span> which had by itself gone up in price and which was definitely misappropriated [by the vendors],<span class="x" onmousemove="('comment',' Who sold it in his absence. ');"><sup>8</sup></span> and regarding this we have learnt that 'All kinds of robbers have to pay in accordance with the value at the time of the robbery'?<span class="x" onmousemove="('comment',' Supra 93b. And the value of the flax at the time of robbery in this case was exactly the amount of the purchase money received for it at the second sale. ');"><sup>9</sup></span> — It may, however, be said that there it was a case of advance payment.<span class="x" onmousemove="('comment',' I.e., when the vendors received the money from R. Kahana they were not yet in possession of flax at all, but acted in accordance with B.M. 72b. ');"><sup>10</sup></span>