Charles Ellicott Commentary Leviticus 10:12

"And Moses spake unto Aaron, and unto Eleazar and unto Ithamar, his sons that were left, Take the meal-offering that remaineth of the offerings of Jehovah made by fire, and eat it without leaven beside the altar; for it is most holy;" — Leviticus 10:12 (ASV)

And Moses spoke to Aaron. —This communication, which refers to the sacrifices offered on the eighth day (the day after the consecration was finished), Moses made to Aaron and his two surviving sons immediately after the calamity that had befallen them. As Aaron lost his two eldest sons because they had violated the sacrificial regulations, Moses is most anxious to guard him and his two younger sons against transgressing any other part of the ritual connected with the same sacrifices, lest they also should incur a similar punishment.

Take the meat offering that remains of the offerings. —The meat offering that was offered by the nation the day after the consecration, when the calamity happened , and which was not yet eaten. With the exception of the handful that was burnt on the altar, all belonged to the priests (Leviticus 6:14–18).

And eat it without leaven beside the altar. —That is, in the court of the tent of meeting, where the altar of burnt offering stood .

For it is most holy. —Hence it could only be eaten by the male members of the priests' families within the court of the sanctuary .