[If] one slaughters [by cutting] one [of the organs] of a bird or both [organs] of an animal, his slaughtering is valid, and the greater part of one [organ] is tantamount to its entirety. R’ Yehudah says: Until he severs the veridin. [If he severs] half of one [organ] of a bird or one and a half [organs] of an animal, his slaughtering is invalid. [If he severs] the greater part of one [organ] of a bird or the greater part of both [organs] of an animal, his slaughtering is valid.

[If] one slaughters two heads at once, his slaughtering is valid. [If] two hold a knife and slaughter, even if one is above and one is below, their slaughtering is valid.