For if ye turn away from after him,.... From following him in the way of his commandments, from attending his word, worship, and ordinances, and from walking after him, who went before them in a pillar of cloud and fire, as it is suggested they would, should they stop short here and not go over Jordan into the land of Canaan:

he will yet again leave them in the wilderness; as he did at the time of the affair of the spies, when they were ordered to turn and get into the wilderness by the way of the Red sea, and where they had been ever since unto this time, Num 14:25,

and ye shall destroy all this people; be the cause of their destruction, if the Lord should in such a manner resent this step of theirs, as to order them back into the wilderness again, though they were now as they were before, on the border of the land of Canaan.

Moses said unto the children of Gad and to the children of Reuben, Shall your brethren go to war, and shall ye sit here--Their language was ambiguous; and Moses, suspicious that this proposal was an act of unbelief, a scheme of self-policy and indolence to escape the perils of warfare and live in ease and safety, addressed to them a reproachful and passionate remonstrance. Whether they had really meditated such a withdrawal from all share in the war of invasion, or the effect of their leader's expostulation was to drive them from their original purpose, they now, in answer to his impressive appeal, declared it to be their sincere intention to co-operate with their brethren; but, if so, they ought to have been more explicit at first.