Reference for Chullin 155:11

כיצד

THUS, IF ONE PERSON SLAUGHTERED AN ANIMAL AND [ANOTHER]<span class="x" onmousemove="('comment',' It is assumed for the sake of clarity that one person slaughtered the dam and another the young. The law would be the same, however, if both animals were slaughtered by the same person; moreover, it is immaterial whether the dam was slaughtered first and then the young or vice versa.');">⁶</span>

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