Sefer HaChinuch ספר החינוך

To not destroy the corner of the beard: To not destroy the corner of the beard, as it is stated (Leviticus 19:27), “and you shall not destroy the corner of your beard.” And there are five corners to the beard, and there is a [separate] liability for lashes for each one, even if he removed them all at once and with one warning. And these are them: the upper and lower jaw on the right; the upper and lower on the left - behold, that is four — and the chin of the beard, and that is the place of connection of the jaws below, which is called menton in the vernacular — behold, that is five. And the language of the Mishnah (Mishnah Makkot 3:5) is “For the beard, five: two from here and two from there and one at their bottom.” And the transcriber wrote in the name of Rambam, may his memory be blessed, (on Sefer HaMitzvot, Negative Commandments 44), “And the prevention came about this with these words, ‘and you shall not destroy the corner of your beard,’ and it did not say, ‘and you shall not destroy your beard’ — even though it is all called the beard. It wanted to say with this that you should not shave even one corner from the whole of the beard. And we administer one [set of] lashes for each one. And even if he shaved all of them at one time, he is liable five [sets of] lashes for it.”

That which we have written on the previous commandment to distance all matter of idolatry is from the roots of the commandment. And this was also a custom of the priests of idolatry, to destroy the corner of their beard. And he also wrote about this — and this is the language of the transcriber: “And that which determines that the five corners of the beard are not counted as five commandments is because the prevention comes with [one] distinct word, and it is [one] distinct subject; as we explained in the commandment before it.” To here [are his words].

From the laws of the commandment is that which they, may their memory be blessed, said (Makkot 21a) that the liability is only with shaving of a blade, as it is stated, “and you shall not destroy” — specifically a shaving that has destruction, and that is a blade. And so did they, may their memory be blessed, explain it. And Rambam, may his memory be blessed, wrote (Mishneh Torah, Laws of Foreign Worship and Customs of the Nations 12:7), “And if he shaved with scissors, he is exempt.” [It appears from his words that he is specifically exempt, but it is (still rabbinically) prohibited to do so. And it is possible that the matter is regarding shaving with scissors that are similar to a blade,] and as the matter appears to be in Tractate Nazir 59b. As they said there, “Rav said, ‘A person may lighten all of his body with a blade’” — and we establish it to be [referring to] scissors similar to a blade; except for the underarm and the pubic area, which is forbidden even thus (this follows the first edition). [And it is permissible to shave the mustache with a blade, as there is no concern of a corner there at all.] And there are some great ones that are stringent not to pass a blade over any of their skin. And the rest of its details are elucidated at the end of Makkot.

And [it] is practiced in every place and at all times by males. But females are permitted regarding destruction of the beard - if they have hair there — [and a woman is exempt also for destroying the beard of man. But slaves are liable for the destruction of the beard], as we have written above (Sefer HaChinukh 251). And so [too], those [the sex of which is in doubt] are forbidden [based on the] doubt.