Reference for Bava Batra 187:6
לעולם חטי ושערי מקבל עפרורית עדשים איצטריכא ליה דסלקא דעתך אמינא כיון דמיעקר עקרי להו יותר מרובע נמי לקבל קא משמע לן
But [since] the reason why lentils [are allowed a full quarter of a <i>kab</i> of sandy matter is] because they are usually plucked while wheat and barley [are] not, infer [then] from this, [that in the case of] wheat and barley [the buyer need] not accept [a full quarter of a <i>kab</i>] of sandy matter!<span class="x" onmousemove="('comment',' Which would confirm the answer given above, in justification of R. Kattina, that of sandy matter, 'less than a quarter'. ');"><sup>11</sup></span> — [It may be retorted that a buyer], in fact, must accept [a full quarter of a <i>kab</i> of] sandy matter [in the case also of] wheat and barley<span class="x" onmousemove="('comment',' The same quantity as that stated in the case of lentils. ');"><sup>12</sup></span>