Jamieson-Fausset-Brown on Numbers 32:28
concerning them Moses commanded--The arrangement itself, as well as the express terms on which he assented to it, was announced by the leader to the public authorities. The pastoral country the two tribes had desired was to be granted them on condition that they would lend their aid to their brethren in the approaching invasion of Canaan. If they refused or failed to perform their promise, those possessions should be forfeited, and they themselves compelled to go across the Jordan and fight for a settlement like the rest of their brethren.
John Gill on Numbers 32:31
And the children of Gad and the children of Reuben answered,...., The word is in the singular number, and shows their unanimity, that they agreed to what Moses said, and replied all of them as one man, as Jarchi expresses it; and it may be there was one that was the mouth of them all, and answered for them:
saying, as the Lord hath said unto thy servants, so will we do; here they make use of the word Jehovah, taking what Moses had said unto them as from the Lord, and therefore should strictly and punctually observe it, as if they heard the Lord himself speak it.
John Calvin on Numbers 32:28-32
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…
Read the whole note in the consoleKeil & Delitzsch on Numbers 32:31-32
The Gadites and Reubenites repeated their promise once more (Num 32:25), and added still further (Num 32:32): "We will pass over armed before Jehovah into the land of Canaan, and let our inheritance be with us (i.e., remain to us) beyond the Jordan."
