וְכָל־בְּהֵמָ֞ה מַפְרֶ֣סֶת פַּרְסָ֗ה וְשֹׁסַ֤עַת שֶׁ֙סַע֙ שְׁתֵּ֣י פְרָס֔וֹת מַעֲלַ֥ת גֵּרָ֖ה בַּבְּהֵמָ֑ה אֹתָ֖הּ תֹּאכֵֽלוּ׃
무릇 짐승 중에 굽이 갈라져 쪽발도 되고 새김질도 하는 것은 너희가 먹을 것이니라
Mishnah Chullin
If an animal was having difficulty giving birth and the fetus put forth a limb and then put it back in, it may be eaten [when its mother is slaughtered]. If it put forth its head, even though it put it back in, it is considered as born. Whatever is cut off from the fetus within the womb [and left inside] may be eaten, but whatever is cut off from the spleen or kidneys [of the animal and left inside] may not be eaten. This is the rule: that which is from the body of the animal is forbidden, but that which is not from the body of the animal is permitted.