וְהָיָ֗ה הַנִּמְלָ֛ט מֵחֶ֥רֶב חֲזָאֵ֖ל יָמִ֣ית יֵה֑וּא וְהַנִּמְלָ֛ט מֵחֶ֥רֶב יֵה֖וּא יָמִ֥ית אֱלִישָֽׁע׃
Wer dann dem Schwerte Hasaëls entrinnt, den wird Jehu töten, und wer dem Schwerte Jehus entrinnt, den wird Elisa töten.
Tze'enah Ure'enah
“Whoever escapes from the sword of Hazael, Jehu will kill” [19:17]. They should kill all those who worship foreign gods and those evildoers that Hazael will let live will be killed by Jehu, and Elisha will kill what Jehu lets live. One should help the other to clean out those who serve foreign gods.
Rashi
Elisha will kill. We do not find that Elisha killed anyone but the forty-two children through the bears in Yericho.11See II Melochim 2:24. Alternatively, the hunger in Shomron was initiated by Elisha’s curse, as implied in II Melochim 6:31.—Ralbag