Sefer HaChinuch ספר החינוך

The commandment of the sacrifice of the zavah when she is healed from her discharge: That the zavah offer her sacrifice after she is healed from her discharge — and it is two doves or two young pigeons, as it is stated (Leviticus 16:28-29), “And if she is purified from her discharge, etc. And on the eighth day, she shall take two doves, etc.”

And the root of this commandment and some of its details are similar to what we have written above (Sefer HaChinukh 179) about this sacrifice. And Rambam, may his memory be blessed, wrote (Sefer HaMitzvot, Positive Commandments 75) that because of [the following] did we consider these two sacrifices of the zav and the zavah as two commandments, even though they are totally [the same] sacrifice — which we have not done with many other sacrifices, as we are not concerned to count each and every sacrifice as a commandment of its own, because of the distinction of who brings them, so long as it is one sacrifice: Because the impurity of these is not the same at all — as the man becomes impure with white and the woman becomes impure with red. And with the opposite, [neither] becomes impure, neither this [one] nor that [one]. And since they are so different, it is fitting to count them as two commandments. And this matter is not at all similar to the metsora and the metsoraat, which is considered one commandment — as tsaraat is the same thing for all of them. And he brought a bit of a proof for his words, from that which they said in Keritot 8b, “There are four who are lacking atonement and these are them: the zav; the zavah; the woman who gave birth; and the metsora.” Behold they counted zav and zavah as two, because they are different in their illnesses; but metsora and metsoraat as one, because the illness is the same in both of them.

And it is practiced at the time of the [Temple]. And one who transgresses and does not bring her sacrifice when she is healed from her discharge has violated this positive commandment, besides that she is lacking atonement.