Reference for Bava Kamma 12:14
ור' ישמעאל אכל שמינה משלם שמינה אכל כחושה משלם שמינה
Would R. Ishmael maintain that the defendant, whether damaging the best or worst, is to pay for the best? — R. Idi b. Abin said: This is so where he damaged one of several furrows and it could not be ascertained whether the furrow he damaged was the worst or the best, in which case he must pay for the best. Raba, however, [demurred] saying: Since where we do know that he damaged the worst, he would only have to pay for the worst, now that we do not know whether the furrow damaged was the best or the worst, why pay for the best? It is the plaintiff who has the onus of proving his case by evidence. R. Aha b. Jacob therefore explained: We are dealing here with a case where the best of the plaintiff's estate equals in quality the worst of that of the defendant;<span class="x" onmousemove="('comment',' The amount of damages, however, would never be more than could be proved to have been actually sustained. ');"><sup>11</sup></span>