The leper shall bring an offering after being declared clean

That is that He commanded us that someone with tsaraat offer a sacrifice when he is healed from it. And that is three animals - a burnt-offering, a sin-offering and a guilt-offering - and a log of oil. But if he was poor, he should offer a lamb for a guilt-offering and two turtledoves or two young pigeons. And this is the fourth of those lacking [full] atonement - and that is His, may He be exalted, saying, "On the eighth day he shall take two flawless male lambs, one one-year old ewe lamb, etc." (Leviticus 14:10). And one will perhaps say, "Why don't you count the sacrifice of those lacking [full] atonement as one commandment, since they all have one thing that brings them all together - and that is their lack of atonement, such that this would be a certain type of purification. And it would have been appropriate for you to say, 'It is x commandment that He commanded us that the purity of some impure ones not be complete until they offer a sacrifice - and that is the zav; the zavah; the woman after childbirth; and one with tsaraat.' Just like you count purification in a mikveh as one commandment - whatever the specific impurity might be - and you don't concern yourself with the type of impurity with which they became impure; so too, would it have been appropriate for you to count the sacrifice of those lacking atonement as one commandment, and we would not be concerned about their [specific] impurities!" God knows that this would no doubt have been appropriate if the sacrifice of each one of these four that lack atonement were the same and did not differ; just like purification in the mikveh is a specific type of purification for every impure one. However as a result of the variation of their sacrifices - as you can see - it is perforce required to count each sacrifice individually. For the thing with which one [of them] completes purification is different from the thing with which the other one completes it. This is like waters of purification (mixed with ashes of a red heifer), the waters of a mikveh and the four species for the one with tsaraat are three commandments, even while they are all to purify the impure - as I will explain. And the regulations of these four that lack atonement and the regulations of their sacrifices have already been explained - in general and in detail - in the eighth chapter of Nazir, at the end of Negaim, in Tractate Kinnim and in scattered places in the Talmud. But most of them and their principles are in the places we named. (See Parashat Metzora; Mishneh Torah, Offerings for Those with Incomplete Atonement 4.)