Thus did your fathers,.... Meaning not particularly and only the fathers of these two tribes he was speaking to, but of them and the other tribes also, who acted much such a part; did not choose to go into the good land to possess it, when they were bid to do it, but were for sending spies first, which brought an ill report of it, and discouraged the people from going into it; the history of which Moses here gives:

when I sent them from Kadeshbarnea to see the land; called only Kadesh, Num 13:26 the reason of the name See Gill on Num 32:13.

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.