Reference for Bava Batra 187:9
ואמרי לה קנסא רובע שכיח יותר לא שכיח ואיהו הוא דעריב וכיון דעריב קנסוהו רבנן בכוליה
but a person does not take the trouble [to sift, if the refuse only amounts to] a quarter [of a <i>kab</i> for every <i>se'ah</i>;<span class="x" onmousemove="('comment',' Rather than have the trouble of sifting. he accepts the comparatively little refuse. ');"><sup>16</sup></span> if] more than a quarter, a person does take the trouble; and, since he takes the trouble [to start sifting], he takes [a little more] trouble with all of it.<span class="x" onmousemove="('comment',' Once the sifting commences, it is not much more trouble to complete the whole. Hence, the buyer exercises his right and demands compensation for all the refuse. ');"><sup>17</sup></span>