Rashi on Numbers 32:28/רש"י על במדבר ל״ב:כ״ח

1. 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."