You shall not go outside the entrance to the Tent of Meeting, or you will die, for the LORD’s anointing oil is on you.” So they did as Moses instructed.
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 ye shall not go out from the door of the tabernacle of the congregation, lest ye die,.... That is, they were not to relinquish the service of the sanctuary, on the account of the death of these relations of theirs, and through grief for it, but go on in it; not Aaron on account of his children, nor his sons on account of their...
The anointing oil of the Lord is upon you - They were consecrated to the Divine service, and this required their constant attendance, and most willing and cheerful service.