According to the mishnah (Ḥullin 2:1), a valid act of sheḥitah for an animal involves the cutting through of the two organs, the food-pipe and the windpipe, and for a bird the cutting through of either one of these. However, the mishnah states, it is not necessary to cut the organ right through but it suffices if the greater part has been cut through. But if only half has been cut through in the case of a bird or only one and a half in the case of an animal, the sheḥitah is invalid.

The Talmudic sugya (Ḥullin 28b–29a), appended to this mishnah, opens with a debate between the third-century Babylonian Amoraim, Rav and R. Kahana, concerning ‘half and half’ (meḥatzah 'al meḥatzah), i.e. (at this stage of the discussion) where the sheḥitah cut was through only half the organ, half remaining as it was without any cutting. Rav said that half and half is counted as ‘the greater part,’ while R. Kahana said that half and half is not counted as the greater part. This receives the following (editorial) analysis. According to Rav, the law given to Moses regarding sheḥitah was: ‘Do not leave the greater part of the organ without sheḥitah.’ But according to R. Kahana the law was rather: ‘Cut through the greater part.’ The meaning presumably is that, according to Rav, there is no rule that for the act of sheḥitah to be valid the greater part must be cut through.