Reference for Chullin 59:17

אלא אי אמרת אינה לשחיטה אלא בסוף כיון דשחט ביה פורתא אידחי ליה מפסח אידך כי קא שחיט שלמים קא שחיט

that the circumstances of the case were these: The owners of this paschal lamb were rendered unclean by a corpse, so that they had to postpone the offering of the paschal lamb until the Second Passover;<span class="x" onmousemove="('comment',' On the fourteenth day of the second month (Iyar) in accordance with Num. IX. 11.');">¹¹</span>

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