2 Samuel 8:3 - Coke's Commentary on the Holy Bible

To recover his border at the river— The Hebrew ידו להשׁיב lehashib yado, may be literally rendered, as he went to turn back his hand, &c. David smote Hadadezer, when he, David, went to turn back his, Hadadezer's, hand, by the Euphrates; i.e. to repel Hadadezer and his forces at the river, and prevent the intended invasion of his dominions. Here then Hadadezer was also the aggressor. In the parallel place, 1 Chronicles 18:3 it is ידו להציב lehatzib yado, to establish his hand, or power, at the Euphrates. He wanted to extend his dominions to the Euphrates; and in order to it, designed to invade those of David which lay nearest to that river. David, therefore, had a right by force to prevent it.