Reference for Bava Kamma 50:4
וקמייתי לה בין לטומאת ערב בין לטומאת שבעה ואמאי אימא אהני ק"ו לטומאת ערב ואהני דיו לאפוקי טומאת שבעה
[days]. But why not argue that the <i>a fortiori</i> well serves its purpose regarding the defilement for a single day,<span class="x" onmousemove="('comment',' [As is the case with the bed of a zab (cf. Lev. XV, 4), since it is derived from zab.] ');"><sup>10</sup></span> whilst the principle of <i>Dayyo</i> is to be employed to exclude defilement for seven days? — He [Rabina] answered him: The same problem had already been raised by R. Nahman b. Zachariah to Abaye, and Abaye answered him that it was regarding mats in the case of a dead reptile<span class="x" onmousemove="('comment',' But not at all regarding corpses; the whole problem thus concerns only defilement for a day; v. infra. ');"><sup>11</sup></span> that the Tanna had employed the <i>a fortiori</i>, and the text should run as follows: 'Whence do we learn that mats<span class="x" onmousemove="('comment',' As mats are not included among the articles referred to in Lev. XI, 32. ');"><sup>12</sup></span>