Halakhah su Levitico 14:10

The law of the commandment of a metsora when he is healed from his tsaraat: That every metsora bring up a sacrifice when he is healed from his illness. And that is three beasts - one for a burnt-offering, one for a sin-offering and one for a guilt-offering - and also a log of oil; and if he is poor, a lamb for the guilt-offering, a tenth of a log of oil and two doves or two young pigeons - one for the sin-offering and one for the burnt-offering. As it is stated (Leviticus 14:10), "And on the eighth day he shall take two unblemished male lambs and one female lamb." And it is written in the section that is after this (Leviticus 14:21), "And if he is poor, etc." And this metsora is called, 'one lacking atonement,' until he sacrifices this sacrifice. And there are four lacking atonement (Keritot 8b): this one that we said; the zav; the zavah; and the woman who has given birth. And the substance of [their being] called lacking atonement is to say that each one of them - even though he is pure from his impurity, immersed and his sun set for him on the seventh day - is still lacking this atonement and he cannot eat the consecrated foods until he sacrifices them on the eighth day. And let it not be difficult upon you why we count the sacrifice of each one of these four as a [distinct] commandment, and do not group them all as one commandment - that we say that the four who are lacking atonement offer a sacrifice, and afterwards they will be atoned; as we say about the purification of the waters of the mikveh, that any impure one immerse, and afterwards he will be pure - and we do not distinguish among the types of impurity to count each one as a commandment. As the matter is because the sacrifices of these four are not the same, and it comes out that the thing that completes the purification of one of them does not complete the purification of the other. And therefore, they counted each one a [distinct] commandment. [But this] is not the case with the waters of the mikveh, as the purification is the same with all of them. So answered Rambam, may his memory be blessed (in Sefer HaMitzvot LaRambam, Mitzvot Ase 77).