2 Samuel 8:3 (BSB)

David also defeated Hadadezer son of Rehob, king of Zobah, who had marched out to restore his dominion along the Euphrates River.

From 2 Samuel 8. Also in the ESV.

Commentary on 2 Samuel 8:3

• Matthew Henry (Presbyterian), Matthew Henry's Complete Commentary on 2 Samuel 8:1-8: God had given David rest from all his enemies that opposed him and made head against him; and he having made a good use of that rest, has now commission given him to make war upon them, and to act offensively for the avenging of Israel's quarrels and the recovery of their rights; for as yet they were not in full possession of that country...
• John Gill (Reformed Baptist), Exposition of the Old and New Testaments on 2 Samuel 8:3: And David also smote Hadadezer the son of Rehob, king of Zobah,.... Called sometimes Aramzobah, and was a part of Syria, as its name shows. Benjamin, of Tudela (h) takes it to be the same with Haleb or Aleppo; Josephus (i) calls it Sophene; but that is placed by Ptolemy (k) beyond the Euphrates; whereas this country must be between that river and the land...
• Jamieson-Fausset-Brown (Reformed), Commentary Critical and Explanatory on the Whole Bible on 2 Samuel 8:3: HE SMITES HADADEZER AND THE SYRIANS. (Sa2 8:3-14) Zobah-- (Ch1 18:3). This kingdom was bounded on the east by the Euphrates, and it extended westward from that river, perhaps as far north as Aleppo. It was long the chief among the petty kingdoms of Syria, and its king bore the hereditary title of "Hadadezer" or "Hadarezer" ("Hadad," that is, "helped").
• Adam Clarke (Methodist), Clarke's Commentary on the Bible on 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.