Reference for Bava Kamma 212:16

ואמר רבי חייא בר אבא א"ר יוחנן הטוען טענת גנב באבידה משלם תשלומי כפל מאי טעמא דכתיב (שמות כב, ח) על כל אבדה אשר יאמר

the reason being that since the judges had already adjudicated on the matter, when he sold or slaughtered the animal he became [in the eye of the law] a robber, and a robber has not to make fourfold and fivefold payments;<span class="x" onmousemove="('comment',' In fact no pecuniary fine at all; cf. supra p. 452. ');">²⁷</span> [but where they merely said to him] 'You are liable to pay him' and after that, he slaughtered or sold the animal he would be liable [to repay fourfold or fivefold], the reason being that since they have not delivered the final sentence upon the matter, he is still a thief!<span class="x" onmousemove="('comment',' Who is subject to the law of Ex. XXI, 37. Why then not give this answer? ');">²⁸</span>

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