Reference for Yevamot 29:15
ר' עקיבא גמריה אסתפק ליה ולא ידע אי ב"ה באחד בשבט אמור או בט"ו בשבט אמור
did act [in accordance with their rulings!] — R. Akiba was uncertain of his tradition, not knowing whether Beth Hillel said the first of Shebat<span class="x" onmousemove="('comment',' Was the new year. Cf. supra nn. 5-7. ');"><sup>40</sup></span> or the fifteenth of Shebat.<span class="x" onmousemove="('comment',' Was the new year. Cf. supra nn. 5-7. ');"><sup>40</sup></span> Mar Zutra raised an objection: It once happened that Shammai the Elder's daughter-in-law was confined with child<span class="x" onmousemove="('comment',' During the Festival of Tabernacles when it is obligatory upon all males to dwell in booths (Lev. XXIII, 42), the roof of which must consist of branches or leaves or any similar material which grows from the ground (v. Suk. 2aff). ');"><sup>41</sup></span>