John Gill Commentary Numbers 32:28

"So Moses gave charge concerning them to Eleazar the priest, and to Joshua the son of Nun, and to the heads of the fathers` [houses] of the tribes of the children of Israel." — Numbers 32:28 (ASV)

So concerning them Moses commanded
That they should have a grant of the land they requested: this looks as if Moses determined the case himself, though perhaps it was by the vote, and with the consent of the whole court; only Moses strictly enjoined them to observe it, namely,

Eleazar the priest, and Joshua the son of Nun, and the chief fathers of
the tribes of the children of Israel;
and the rather he did this, because he knew that he should die, and not see either the thing itself or the conditions of it performed.