Once a year Aaron must make peace with the Lord by putting blood on its horns. Once a year—for generations to come—blood from the offering must be placed on the altar to make peace with the Lord. It is most holy to the Lord.”
Also, when Aaron lights the lamps at dusk, he must burn incense. For generations to come an incense offering must burn constantly in the Lord’s presence.
Aaron’s sons Nadab and Abihu each took an incense burner and put burning coals and incense in it. Then in the Lord’s presence they offered this unauthorized fire.