Halakhah zu Wajikra 14:9

And afterwards, the priest shaves the metsora. And how does he shave him? He passes the razor over his visible flesh - and even [on] the underarm and the pubic area and all the rest of the body - until he becomes [smooth] like a gourd, as it is stated (Leviticus 14:9), "all of his hair." If so, why does it state, "his head, his beard, and his eyebrows?" To include everything that is like them and to exclude hair that is in the nose, since it is not seen. And afterwards he washes his clothes and immerses, and is purified with this from passing on impurity from his resting and sitting [upon something]; and he can come inside the [city] wall. And he counts seven days; and during those seven days, he is prohibited in sexual relations, as it is stated, "outside of his tent" - teaching he is forbidden in sexual relations. But a metsora'at is permitted in sexual relations. All of these seven days, he is still a source of impurity and renders a person and vessels impure with touch, but he does render impure with carrying - as behold it states (Leviticus 14:9), "And it shall be on the seventh day, etc. and he shall wash his clothes" - teaching that he was rendering clothes impure. And [just] like he was rendering clothes impure, so [too] was he rendering a man impure with touch - since all that renders a person impure, renders clothes impure; and all that does not render a person impure, does not render clothes impure (Mishnah Kelim 1:1). And on the seventh day, the priest shaves him a second [time] like the first shaving. And [the metsora] washes his clothes and immerses and is purified from rendering others impure. And behold he is like all who have immersed during the day, and can eat from the tithe; when his sun sets, he can eat from the priestly tithe; [and] when he brings his atonement, he can eat from consecrated foods. The slaughter of the bird, the shaving and the sprinkling are during the day, but all the other procedures are whether during the day or during the night. These [three things] are with men, but all the rest are even with women. These are with priests, but all the rest are even through an Israelite. And it is a commandment for the same priest who rendered him impure [to render him pure, as it is stated (Leviticus 13:59)], "to render him pure or to render him impure." And the rest of its details are in Tractate Negaim.

The commandment of shaving the metsora on the seventh day: That the metsora shave all of his hair - and that is the second purification, as they, may their memory be blessed, said in Negaim (Mishnah Negaim 14:3) - as it is stated (Leviticus 14:9), "And it shall be on the seventh day and he shall shave all of his hair, etc." And they, may their memory be blessed, said (Mishnah Negaim 14:4), "Three shave, and their shaving is a commandment: the nazirite; the metsora; and the Levites." And the Levites require [the same] shaving as the metsora, and it was in the wilderness (after the Exodus).

From its laws is that which they, may their memory be blessed, said (Sotah 16a), "How is the shaving? He passes the razor over his visible flesh - and even [on] the underarm and the pubic area and all the rest of the body - until he becomes [smooth] like a gourd, as it is stated (Leviticus 14:9), 'all of his hair.'" And when he shaves the two shavings, he only shaves with a razor. But if he shaved not with a razor - or he left two hairs - [it is as if] he has not done anything. And the rest of its details are in Tractate Negaim (see Mishneh Torah, Laws of Defilement by Leprosy 10).