וַיַּ֣ךְ דָּוִ֔ד אֶת־הֲדַדְעֶ֥זֶר בֶּן־רְחֹ֖ב מֶ֣לֶךְ צוֹבָ֑ה בְּלֶכְתּ֕וֹ לְהָשִׁ֥יב יָד֖וֹ בִּֽנְהַר־[פְּרָֽת׃]
Rashi on II Samuel
To enlarge his border. As [Yonasan] translates, "To widen his border," [Haddadezer] conquored land outside his countries border and widened his border.