Commentary for Numbers 32:28

. ויצו להם AND HE GAVE CHARGE — This is the same as, and he gave charge concerning them. The words imply: and to watch over the fulfilment of the agreement they had made he appointed Eleazar and Joshua. The use of the ל in להם here is the same as in (Exodus 14:14): “The Lord will fight לכם for you."

ויצו להם, Moses now commanded not to give to these two tribes the lands of Sichon and Og until they would return from conquest of the lands on the west bank of the river Jordan. This is the meaning of verse 22. The two tribes did not accept this arrangement and said נחנו נעבור חלוצים (verse 32) on condition that אתנו אחזת נחלתנו, that simultaneously we will be in possession of our ancestral inheritance. As soon as we shall cross the river Jordan these lands will be legally ours!

Like עליהם [concerning them]. This command was in the sense of appointing, as Rashi subsequently writes, thus the word להם ["to them"] is inappropriate, rather it should have said עליהם ["concerning them"]. Therefore Rashi says “like עליהם.” Since they were only appointed based on certain conditions, he adds “and their stipulation.” He says that we find the word להם ["to" or "for you"] meaning “concerning you” as in “Hashem will fight for you” which means עליכם ["concerning you"] as if to say “on your behalf.”