John Gill Commentary Numbers 1:17

"And Moses and Aaron took these men that are mentioned by name:" — Numbers 1:17 (ASV)

And Moses and Aaron took these men
They doubtless sent for them, and acquainted them with the nomination of them, by the Lord himself, for such a service; and they took them with them to the place where the number of the people was to be taken:

which are expressed by [their] names :
in (Numbers 1:16) , and that as declared by the mouth of God himself.