If a knife with a notch in the blade is used for ritual slaughter, the slaughter is invalid. To prevent this from happening, the knife is inspected before each and every use. On today’s daf, Rav Hisda asks:
From where in the Torah is it derived that examination of a knife is an obligation?
It is stated: “Slaughter with this and eat” (1 Samuel 14:34).
Rav Hisda asks for a verse from the Torah that explains the requirement to inspect the knife with every slaughter, but he is given one from the Prophets. This is not an unprecedented maneuver for the Gemara, especially when, as in this case, there is no verse in the Torah that establishes the practice.
Let’s take a closer look at the context in 1 Samuel: The Israelites are engaged in battle with the Philistines. King Saul has commanded them not to eat until the battle is won. The Israelite army emerges victorious but hungry, and their king commands, “everyone must bring me his ox or his sheep and slaughter with this and eat. You must not sin against God and eat with the blood.” Saul seeks to ensure that his army upholds the dietary standards established by God, including the prohibition of consuming the blood of an animal. When Saul says “slaughter with this,” the Gemara suggests, he is referring to a knife that he himself has inspected. That he requires each soldier to bring their animal to him for slaughter suggests that he will inspect the knife before each slaughter — evidence that the examination of the knife is a requirement.
Having provided an answer, the Gemara raises an objection to Rav Hisda’s question:
Isn’t it obvious that a knife must be examined before slaughter? If one were to create a perforation in the gullet, the animal would be a treifa, therefore the knife requires examination to prevent that situation.
In other words, we don’t need a verse to support this practice — it is obvious that we should do it. Failure to do so would increase the number of invalid slaughters and prohibit the meat from being consumed. To prevent the waste and honor the process of ritual slaughter, examining the knife is a must.
This leads to a new challenge: If it is obvious that we have to do this, why would Rav Hisda be asking for a source to support the practice? Perhaps, suggests the Gemara, he is not asking about the practice as a whole, but the tradition that arose that we should ask a Torah scholar to perform the inspection instead of the butcher. If so, the verse that was cited is an apt one: Just as King Saul inspected the knife for each of his soldiers, so too should a Torah scholar inspect the knife for the slaughterers in his area.
This would be all well and good if not for the teaching of Rabbi Yohanan that we only show the knife to a Torah scholar out of deference — not a Torah-based obligation. In light of this teaching, the Gemara concludes that the requirement to check the knife is rabbinic in nature and the biblical verse is merely a support for the practice, not a source.
It turns out that there is no biblical requirement for the practice of inspecting the knife. Yet, it is rabbinically required anyway to help ensure that the slaughter yields a positive outcome: edible meat.
The obligation to examine the knife is codified into law and is a requirement that falls upon the shochet (ritual slaughterer). This makes sense, especially as the practice shifted from the mishnaic suggestion that “everyone can slaughter” to a world in which those who perform ritual slaughters have to be certified. This makes shochets necessarily Torah scholars in their own right.
Read all of Chullin 17 on Sefaria.
This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on May 17, 2026. If you are interested in receiving the newsletter, sign up here.
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