Leviticus 10:6

And Moses said unto Aaron and unto Eleazar and unto Ithamar, his sons, Uncover not your heads, neither rend your clothes, the usual manner of showing a high degree of mourning being to let the hair of the head grow without trimming and cutting and to tear open the garments over the breast, lest ye die, and lest wrath come up on all the people. A transgression of the high priest, as the mediator between God and the people, involved the latter in the punishment of God. To mourn in this case would have been equivalent to expressing dissatisfaction with the judgments of the Lord and would have brought His punishment upon the offenders and upon all whom they represented. But let your brethren, the whole house of Israel, bewail the burning which the Lord hath kindled, the terrible expression of God's wrath in destroying the priests, the sad calamity that had befallen them.