For fear of this thing - The motive that actuated us was directly the reverse of that of which we have been suspected.

For the Lord hath made Jordan a border between us and you,.... And by it separated them from them, as if they were a distinct people; not that this was really the case, but so they feared it would be represented in time to come; for though Jordan was the border of the land of Canaan, strictly so called, eastward, Num 34:12; yet it did not exclude the land of the two tribes and a half from being part of the land of promise; for the Amorites, which before inhabited it, and were driven out of it, were Canaanites, and were one part of the people, whose land the Lord promised to Abraham, Gen 15:18,

ye children of Reuben, and children of Gad, have no part in the Lord; in his covenant and promises, in his worship, word, and ordinances; these are things you have nothing to do with, being separated from us his peculiar people; or "have no part in the Word of the Lord", as the Targum, the promised Messiah, being without, or separated from him, as the Gentiles are said to be, Eph 2:12,

so shall your children make our children cease from fearing the Lord; from worshipping the Lord, the fear of the Lord being often put for the whole worship of God, external and internal, Ecc 12:13; by behaving in the above manner towards them, they would be the cause and occasion of their apostasy from the true God, and it would be in effect to say to them, "go, serve other gods", Sa1 26:19.

Then the children of Reuben . . . answered--repudiating, in the strongest terms, the alleged crime, and deponing that so far from entertaining the intention imputed to them, their only object was to perpetuate the memory of their alliance with Israel [Jos 22:24-25], and their adherence to the worship of Israel's God [Jos 22:26-27].