Reference for Bava Batra 186:9

ממאי דלמא איפכא הא לא קשיא כל תנא בתרא לטפויי מילתא קא אתי

is of the opinion [that the] expenses also [must be refunded]! — How [can this be proved]? Is it not possible [that the opinions of the two Tannaim are to be] reversed?<span class="x" onmousemove="('comment',' The first Tanna holding the seller responsible for the expenses whilst R. Simeon does not. Those 'others' will not therefore be R. Simeon but the first Tanna of our Mishnah. ');">¹⁴</span> This is no difficulty. Any Tanna [who is mentioned] last, enters [the discussion for the purpose of] adding some [restriction];<span class="x" onmousemove="('comment',' In this case, R. Simeon, who is last, must therefore be the one who adds the expenses to the seller's responsibility. ');">¹⁵</span>

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