Reference for Bava Batra 189:9

אי דאמר ליה מרתף זה קשיא דתניא מרתף של יין אני מוכר לך נותן לו יין שכולו יפה מרתף זה של יין אני מוכר לך נותן לו יין הנמכר בחנות מרתף זה אני מוכר לך אפילו כולו חומץ הגיעו

from the very beginning; only. [since] less than a sixth is not noticeable, a person does not mind to forego it; a sixth, [however], [since it] is noticeable, one does not forego; [while] more than a sixth is a purchase based on error and is to be entirely cancelled.<span class="x" onmousemove="('comment',' In the case of refuse in produce, however, the buyer is always ready to accept a certain quantity of it, (a quarter of a kab of refuse per se'ah of produce). He may, therefore, also be assumed to accept this quantity even when more refuse has been found, provided the surplus has been refunded. ');">¹⁶</span> Come and hear! [It has been taught:] [If] one undertakes to plant another's field,<span class="x" onmousemove="('comment',' Lit., 'receives a field from another to plant'. ');">¹⁷</span>

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