Halakhah su Levitico 14:4

Sometimes there will be a command which is one commandment, but it has many parts - such as the commandment of lulav, which has four species. Behold that we do not say that (Leviticus 23:40), "the fruit of goodly trees," is a separate commandment; "the boughs of thick trees," are a separate commandment; and "willows of the brook," are a separate commandment. For they are all parts of the [one] commandment - since He commanded to combine them. And after they are combined, the commandment is to take all of them into the hand on the designated day. And by the exact same comparison, it is inappropriate to count His saying about purifying someone with tsaraat - that it is with (Leviticus 14:4-5) two living birds, cedar wood, hyssop, fabric dyed scarlet, living water and a ceramic vessel - as six commandments. Rather purifying someone with tsaraat is one commandment in all of its description, and all of these requirements and others - meaning, shaving. For all of these are parts of the commandment that we have been commanded - being the purification of someone with tsaraat - and that is that it be done in the prescribed way. And the exact same comparison applies to that which He commanded us to do regarding recognition of someone with tsaraat - while he is impure - so that he is kept away from. And that is His saying, "his clothes shall be rent, his head shall be left bare, and he shall cover over his upper lip, etc." (Leviticus 13:45). And none of these acts are a separate commandment, but it is rather their combination that is the commandment - and that is that we are commanded to bring about recognition of someone with tsaraat, such that someone who sees him stay away from him; and that his recognition be with this and that. This is like that which we have been commanded to rejoice in front of the Lord on the first day of Sukkot - and its explanation was that the joy be in the taking of this and that (the four species of the lulav).

From the laws of the commandment is that which they, may their memory be blessed, said (Zevachim 70a) that Scripture did not distinguish with an impure beast or animal between its meat and its chelev - as it is all forbidden. And [regarding] flesh of a person, his flesh is not included in the prohibition of an impure beast, to transgress a negative commandment for it, even though man is called a living (or animal) soul and he does not bring up the cud or completely divide [his foot]. And therefore, we do not administer lashes for one who eats from his flesh or drinks from his chelev - whether alive or dead. But it is nonetheless forbidden with a positive commandment, as behold Scripture numbered seven species of animals and stated about them (Leviticus 14:4), "this is the animal that you may eat." And a negative commandment that comes from the implication of a positive commandment, is a positive commandment. This is the opinion of Rambam, may his memory be blessed (Mishneh Torah, Laws of Forbidden Foods 2:3). But Ramban, may his memory be blessed, wrote (Ramban on Leviticus 11:3) that there is not even a positive commandment about the flesh of a man. And he brought a proof from that which they, may their memory be blessed, said (Keritot 21a), "There is not even a commandment of separation from the blood and chelev of those that walk on two [legs]." And he, may his memory be blessed, wrote that the law is the same for flesh, that it is permitted like the blood. As if not, how could blood be permissible - and as they, may their memory be blessed, said (Keritot 22a), "Blood that is between the teeth, he should suck and swallow" - and it is established for us (Bekhorot 5a) "All that comes out of the impure is impure." And nonetheless, the flesh of the dead (Israelite) is forbidden to benefit from. And the rest of his proofs are in his book. And the rest of the details of the commandment are elucidated in the third chapter of Chullin and in other places (see Mishneh Torah, Laws of Forbidden Foods 2).

From the laws of the commandment is that which they, may their memory be blessed, said (Mishnah Negaim 14:1), "How does one purify the metsora? He would bring a new earthenware pitcher and place within it a reviit of living water," with which it would be fitting to consecrate the sprinkling water - and that measure is [rabbinic] (Sotah 16b) - "and he would bring two wild birds" that are pure, for the sake of the purification of the metsora; as it is stated (Leviticus 14:4), "and it shall be taken for the one being purified." He slaughters the clarified (meaning, choice) of the two of them upon the water in the earthenware vessel and squeezes until the blood is recognizable in the water. And he digs and buries the slaughtered bird before him - and this is a tradition from what was heard. He takes cedar wood - and its commandment is that it be an ell long and its width be like a quarter of a foot of the feet of a bed; and not less than a handbreadth of hyssop that does not have an adjunct name; wool dyed red, the weight of which is a shekel, and if he mixed [its color], he disqualified it, like the dying of the aquamarine, which is disqualified by mixing. And all the measures are a law [from Moshe at Sinai] (Eruvin 4a). And he takes the living bird with the three of them; and the four species impede one another (Menachot 27a); and cedar wood or hyssop that have been peeled are disqualified. He ties the hyssop to the cedar wood with a strip of crimson fabric and surrounds them with the tips of the wings and the tip of the tail of the living bird. And he dips the four of them in water that is in the vessel and in the blood that is [in] it; "and sprinkles seven times on the back of the hand of the metsora." And he sends away the bird. And how does he send it away? If he is standing in the city, he throws it out of the wall (Kiddushin 57b). "He does not face the sea nor the city, but the desert, as it is stated (Leviticus 14:53), 'to outside the city toward the field'"(Mishnah Negaim 14:2). [If] he sent it and it comes back, he again sends it away - even a hundred times.