Not mourning for the death of one’s family might seem unnatural, but it stands to reason that when the priests have been committed to the Lord, they are responsible to align themselves with him even when members of their family face his judgment. Since the death of Nadab and Abihu resulted from their disobedience to the Lord’s commands, mourning them would imply allegiance to Nadab and Abihu. Wenham suggests, “Had they joined in the traditional customs of tearing their clothes, they might have been tempted in their grief to blame God for their brothers' death.”1
6 And Moses said to Aaron and to Eleazar and Ithamar his sons, “Do not let the hair of your heads hang loose, and do not tear your clothes, lest you die, and wrath come upon all the congregation; but let your brothers, the whole house of Israel, bewail the burning that the LORD has kindled.