Then Moses said to Aaron and his sons Eleazar and Ithamar, “Do not let your hair become disheveled and do not tear your garments, or else you will die, and the LORD will be angry with the whole congregation. But your brothers, the whole house of Israel, may mourn on account of the fire that the LORD has ignited.
We may well think that when Nadab and Abihu were struck with death all about them were struck with horror, and every face, as well as theirs, gathered blackness. Great consternation, no doubt, seized them, and they were all full of confusion; but, whatever the rest were, Moses was composed, and knew what he said and did, not being displeased, as David was in a like case, Sa2 6:8.
Commenting on Leviticus 10:3-7
And Moses said unto Aaron, and unto Eleazar, and unto Ithamar, his sons,.... His two younger sons, which yet remained; and so the Septuagint version adds, as in Lev 10:12. uncover not your heads; that is, do not take off your mitre, as the Septuagint version; or the bonnets which they wore in the time of their ministry; for the Jewish priests always had their...
Uncover not your heads--They who were ordered to carry out the two bodies, being engaged in their sacred duties, were forbidden to remove their turbans, in conformity with the usual customs of mourning; and the prohibition "neither rend your garments," was, in all probability, confined also to their official costume.