2-samuel 8:3

David smote - Hadadezer - He is supposed to have been king of all Syria, except Phoenicia; and, wishing to extend his dominions to the Euphrates, invaded a part of David's dominions which lay contiguous to it; but being attacked by David, he was totally routed.

Hadadezer - Not (see the margin) Hadarezer. Hadadezer, is the true form, as seen in the names Benhadad, Hadad (1 Kings 15:18, etc.; 1 Kings 11:14, etc.). Hadad was the chief idol, or sun-god, of the Syrians.

To recover his border - literally, to cause his hand to return. The phrase is used sometimes literally, as e. g. Exodus 4:7; 1 Kings 13:4; Proverbs 19:24; and sometimes figuratively, as Isaiah 1:25; Isaiah 14:27; Amos 1:8; Psalm 74:11. The exact force of the metaphor must in each case be decided by the context. If, as is most probable, this verse relates to the circumstances more fully detailed in 2 Samuel 10:15-19, the meaning of the phrase here will be when he (Hadadezer) went to renew his attack (upon Israel), or to recruit his strength against Israel, at the river Euphrates.

8:3 As he went - David, remembering the grant which God had made to his people of all the land as far as Euphrates, and having subdued his neighbouring enemies, went to recover his rights, and stablish his dominion as far as Euphrates.