Charles Ellicott Commentary Leviticus 10:6

"And Moses said unto Aaron, and unto Eleazar and unto Ithamar, his sons, Let not the hair of your heads go loose, neither rend your clothes; that ye die not, and that he be not wroth with all the congregation: but let your brethren, the whole house of Israel, bewail the burning which Jehovah hath kindled." — Leviticus 10:6 (ASV)

Uncover not your heads. —Better, let not your heads be dishevelled. It was the custom for mourners to let their hair grow long, and let it fall in a disorderly and wild manner over the head and face. (Leviticus 21:10; 2 Samuel 15:30; 2 Samuel 19:4, and others.) For this reason the priests who are consecrated to the service of the Lord are even on ordinary occasions not to shave their heads nor permit their locks to grow long. (Ezekiel 44:20) On this occasion especially, Aaron and his two surviving sons are forbidden to give way to these manifestations of grief, since it might be considered as a reflection upon the justice of the punishment.

Neither rend your clothes. —This was another ordinary manifestation of sorrow and mourning. (Genesis 37:34; Joshua 7:6; 2 Samuel 13:21, and others.) To this day the Jews observe this custom of mourning for the death of their near relations; they tear their garments, let their hair and nails grow, and do not wash.

And lest wrath come upon all the people. —The transgression of this command would not only bring down upon Aaron and his sons the same awful judgment, but would expose the whole community to the Divine wrath. By virtue of the intimate connection which existed between the representative of the nation and the people, a sin committed by the high priest in his official position involved the whole community, and they had to share the consequences of the offence. (See Leviticus 4:3.)

But let your brethren. —The afflicted relatives were, however, not to be deprived of all the customary expressions of mourning. The whole house of Israel, who are here deliberately called “the brethren” of the bereaved, to show the depth of their sympathy, were allowed to mourn over the great calamity which had thus befallen them.