וזבחת … כאשר צויתך THEN THOU MAYEST SLAUGHTER … AS I HAVE COMMANDED THEE — This teaches us that there was already a commandment regarding the slaughtering of animals — as to how one should slaughter; it is not written in the Torah but it comprises the traditional regulations regarding the slaughter of animals that were given orally (נאמרו) to Moses on Mount Sinai (Sifrei Devarim 75:7; Chullin 28a).

The Gemara asks: Who is the tanna who disagrees with Rabbi Elazar HaKappar and holds that the slaughter of a bird is obligatory by Torah law? It is Rabbi Yehuda HaNasi, as it is taught in a baraita: Rabbi Yehuda HaNasi says: The Torah states: “And you shall slaughter of your herd and of your flock, which the Lord has given you, as I have commanded you” (Deuteronomy 12:21). This verse teaches that Moses was previously commanded about the halakhot of slaughter, even though they are not written explicitly in the Torah. He was commanded about cutting the gullet and about cutting the windpipe, and about the requirement to cut the majority of one siman for a bird, and the majority of two simanim for an animal.

That is that He commanded us to slaughter a beast, animal or bird and then to eat its meat; and that it only be permissible to eat their meat by slaughtering [it]. And that is His, may He be blessed, saying, "and you may slaughter any of the cattle or sheep" (Deuteronomy 12:21). And the language of the Sifrei (Sifrei Devarim 75) is, "'And you may slaughter' - just as offerings are with slaughtering; so too, mundane animals are with slaughtering. [...] 'As He commanded you' - [this] teaches that Moses was commanded about the gullet and windpipe, and about the [cutting of] the majority of one [of these being the criterion for proper slaughter] in a bird and the majority of both, in a beast." And the regulations of this commandment and its analysis have already been explained in Tractate Chullin. (See Parashat Re'eh; Mishneh Torah, Ritual Slaughter 1.)

The slaughter which the Torah mentions without elaboration must be explained so that we know: a) which place in the animal is [appropriate] for ritual slaughter?, b) what is the measure of the slaughtering process?, c) with what do we slaughter?, d) when do we slaughter?, e) in which place [on the animal's neck] do we slaughter? f) how do we slaughter, g) what factors disqualify the slaughter? h) who can slaughter?
We were commanded concerning all of these factors in the Torah with the verse [Deuteronomy 12:21]: "And you shall slaughter from your cattle... as I commanded you." All of these factors were commanded to us orally as is true with regard to the remainder of the Oral Law which is called "the mitzvah," as we explained in the beginning of this text.

The slaughterer must slaughter in the center of the neck. If he slaughters to the side, it is acceptable.
What is the measure of slaughter? That one [cut] the two identifying marks, the windpipe and the gullet. Superior slaughter involves cutting both of them, whether for an animal or a fowl and a slaughterer should have this intent. [After the fact,] if one cut the majority of one of them for a fowl and the majority of both of them for an animal or a beast, the slaughter is acceptable.

When one cut one sign entirely and half of the other sign when slaughtering an animal, his slaughter is unacceptable. If he cut the majority of both signs, even though in each instance he cuts only a hair's breadth more than half, it is acceptable. Since he cut even the slightest amount more than half, he has cut the majority.

With what can we slaughter? With any entity, with a metal knife, a flint, glass, the edge of a bulrush, or the like among the entities that cut. [This applies] provided its edge is sharp and does not have a barb. If, however, there was a spike at the edge of the entity with which one slaughters, even if the spike is very small, the slaughter is unacceptable.

When a knife ascends and descends [in a curve] like a snake but does not have a blemish, one may slaughter with it as an initial and preferred option. When the edge of a knife is smooth, but is not sharp, one may slaughter with it, since it does not have a blemish. Even though one passes it back and forth the entire day until the slaughter [is completed], the slaughter is acceptable.

A slaughterer must check the knife at its tip and at both of its sides [before slaughtering]. How must he check it? He must pass it over and draw it back over the flesh of his finger and pass it over and draw it back over his fingernail on three edges, i.e., its tip and both of its sides so that it will not have a blemish at all. [Only] afterwards, should he slaughter with it.

It must [also] be inspected in this manner after slaughter. For if a blemish is discovered on it afterwards, there is an unresolved doubt whether the animal is a nevelah. For perhaps [the knife] became blemished [when cutting] the skin and when he cut the signs, he cut them with a blemished knife.
For this reason, when a person slaughters many animals or many fowl, he must inspect [the knife] between each [slaughter]. For if he did not check, and then checked [after slaughtering] the last one and discovered [the knife] to be blemished, there is an unresolved doubt whether all of them - even the first - are nevelot or not.

The slaughter of ordinary animals does not require focused attention. Even if one slaughtered when [wielding a knife] aimlessly, in jest, or [even] if he threw a knife to implant it in the wall and it slaughtered an animal as it was passing, since it slaughtered properly in the appropriate place and with the appropriate measure, it is acceptable.

Accordingly, when a deafmute, an emotional or an intellectual unstable individual, a minor, a drunk whose mind is befuddled, a person who became overtaken by an evil spirit slaughters and others observe that he slaughters in the correct manner, [the slaughter] is acceptable.
If, by contrast, a knife falls and slaughters [an animal] on its way, it is not acceptable even if it slaughtered it in [the appropriate] manner. For [Deuteronomy, loc. cit.] states: "You shall slaughter," implying that a man must slaughter. [His actions are acceptable,] even if he does not intend to slaughter.

There are five factors that disqualify ritual slaughter and the fundamentals of the laws of shechitah are to guard against each of these factors: They are: shehiyah, dirasah, chaladah, hagramah, and ikur.

[Even] when a Jew knows the laws of ritual slaughter, he should not slaughter in private as an initial and preferred option until he slaughters in the presence of a wise man many times until he is familiar and ardent. If, however, at the outset, he slaughtered in private, his slaughter is acceptable.

When one knows the laws of ritual slaughter and slaughters in the presence of a wise man until he becomes familiar with ritual slaughter, he is called an expert. Any expert may slaughter in private as an initial and preferred option. Even women and servants may slaughter as an initial and preferred option.