Numbers 32:28

28.So concerning them Moses commanded. Moses annexes these conditions to his decision, lest, when the Reubenites and their companions had performed their military tasks:, they should be falsely alleged to have passed over Jordan for the purpose of seeking a new home; whilst at the same time, if they should deceive the other tribes, he provided that their cowardice and deceit should not profit them. In short, if they assisted their brethren in pursuance of their agreement, he commands that the territory, which he now grants them, should always remain theirs; but, if they departed from their promise, he would have them forced against their will to participate in the common allotment. For he does not assign them this portion in the midst of Canaan as a reward for their inertness, in case they should stay behind; but signifies that they should be forcibly and authoritatively carried onwards, so as to be subject to their brethren under all circumstances; since it, was not lawful for them to consult their own separate interests.

In laying down rules for the division of the land, as if it were soon to happen, he encourages the minds of all to confidence, so that they should more cheerfully hasten to pass over; as if the victory were not only already in their hands, but that the fruits of it were soon to be enjoyed.