Albert Barnes Commentary 1 Kings 19:17

"And it shall come to pass, that him that escapeth from the sword of Hazael shall Jehu slay; and him that escapeth from the sword of Jehu shall Elisha slay." — 1 Kings 19:17 (ASV)

Compare the marginal references.

Shall Elisha slay - that is, with a spiritual slaying by the “word of the Lord,” which is sharper than any two-edged sword, and may be said to slay those whose doom it pronounces (compare the marginal reference; Jeremiah 1:10). Elisha does not seem, like Elijah, to have executed God’s judgments on the guilty.