Comentario sobre Levítico 16:13

על האש UPON THE FIRE which was in the censer.

Which is within [the incense-pan]. [Rashi says this] to preclude explaining that there was another fire “before Adonoy” onto which he put the incense. Therefore he explains that he places the incense “’on the fire’ which is within the incense-pan.” “Before Adonoy” means [that he put the incense on the fire] inside [the Holy of Holies] and not outside like the opinion of the Sadducees.

ונתן את הקטורת, “he will place the incense, etc.” this incense has been mentioned in verse 2 where G-d explained that he will be making an appearance above the lid of the Holy Ark, beyond the dividing curtain. At that point, Aaron, and of course, anyone of lower rank, is not to go there on pain of death unless commanded to do so by G-d. G-d had made clear that no human being while inside a body can ever have a visual image of His essence. In order to make this point quite clear the Torah writes that the cloud of the smoke from the incense will fill that area so that nothing can be seen.

ולא ימות THAT IIE DIE NOT — Hence, if he did not offer it according to regulation he was liable to the death penalty (Sifra, Acharei Mot, Chapter 3 10; Yoma 53a).

If he did not do it properly. I.e., he did not put in all its ingredients according to their weight. Even if he did not do like the Sadducees, but placed the incense on the fire within the incense-pan after entering, even so, if he omitted some of its ingredients, either the ingredients themselves or [part of] their weight, he is liable for death. Rashi writes, “If he did not do it properly...,” since it is obvious that from the negative, one can infer the positive.

That is that He commanded us that any man who is healed from a discharge offer a sacrifice. And this is the sacrifice of the zav; and he is lacking [full] atonement until he offers it. And that is His, may He be exalted and may His name be blessed, saying, "When one with a discharge becomes clean of his discharge [...]. On the eighth day he shall take two turtledoves" (Leviticus 15:13-14). (See Parashat Metzora; Mishneh Torah, Offerings for Those with Incomplete Atonement 1-3.)