Deuteronomy 3:16

Half the valley — Or rather to the middle of the river: for the word rendered half signifies commonly middle, and the same Hebrew word means both a valley and a brook or river. And this sense is agreeable to the truth, that their land extended from Gilead unto Arnon, and, to speak exactly, to the middle of that river; for as that river was the border between them and others, so one half of it belonged to them, as the other half did to others, Joshua 12:2. The same thing is expressed in the same words in the Hebrew which are here, though our translators render the self — same words there, from the middle of the river, which here they render, half of the valley. There the bounds of Sihon's kingdom, which was the same portion here mentioned as given to Reuben and Gad, are thus described, from Aroer, which is upon the bank of the river of Arnon, and from the middle of the river, and from half Gilead, even unto the river Jabbok, which is the border of the children of Ammon.