Kosher slaughter requires a single, clean stroke that kills, which necessitates an incredibly sharp knife; however, that’s not the only important factor. Today’s daf discusses several cases of slaughtering with a less-than-ideal knife, one of which is a knife used for idol worship:
Rav Nahman says that Rabba bar Avuh says: With a knife used for idol worship, it is permitted to slaughter an animal with it, but it is prohibited to cut meat with it. It is permitted to slaughter an animal with it because slaughtering is a destructive action. But it is prohibited to cut meat with it, because that is a constructive action.
It’s forbidden to derive benefit from objects used for idol worship, which would at first glance seem to prohibit any use of the knife at all. But Rabba bar Avuh says that slaughter is a destructive act, and therefore does not constitute benefit. For many, that argument may appear unintuitive, given that slaughter is an intentional act, and the animal’s death is a desired outcome. Rashi explains that since the animal is worth more while alive than dead, slaughter diminishes its value, and is therefore “destructive” and not a form of benefit. Once the animal has been slaughtered, however, cutting meat is a constructive act, because it facilitates consumption. Therefore, using the knife for this purpose is forbidden.
The Gemara challenges the presentation of this halakhah and makes a different suggestion:
Derive that it is prohibited to use a knife used for idol worship due to the residue of fat of forbidden carcasses!
The Gemara is baffled as to why we’re discussing hana’ah, benefit, when we should be worried about the actual treyf fat on the knife! Presumably a knife used for idol worship is one used to slaughter idolatrous sacrifices, in which case we should be worried that it retains residues from unkosher animals. The Gemara has a convenient rejection:
He is referring to the case of a new knife.
There’s no residue, suggests the Gemara, because the knife has never been used! But this produces a different problem:
If it is a new knife, both according to Rabbi Yishmael and according to Rabbi Akiva, it is merely in the category of accessories of idol worship, and accessories of idol worship are forbidden only after they are used for idol worship.
Everyone agrees that something that’s only an accessory to worship, such as a knife used to slaughter sacrifices, does not become forbidden until its first usage. If we’re talking about a new, clean knife, there shouldn’t be any issue whatsoever. The Gemara therefore provides two alternative answers:
If you wish, say that this is a case where he cut a branch for idol worship with the knife.
And if you wish, say it is referring to the case of an old knife that he burned until it became white hot in the fire.
For there to be any issue at all, we must be dealing with a knife that was already used for idol worship, but for the concern to be purely one of benefit, it can’t have any treyf animal residue. Therefore, says the Gemara, one option is that the knife cut branches subsequently used in idolatrous worship. The other option is that the knife was kashered with heat, a technique known as libun, purging all residues of idolatrous meat. Though these might seem like rather limited cases, the Gemara is forced to assume them in order to explain the limited scope of Rabba bar Avuh’s statement.
Read all of Chullin 8 on Sefaria.
This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on May 8, 2026. If you are interested in receiving the newsletter, sign up here.
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