1 Kings 18:40 - Wesley's Explanatory Notes

Elijah said — He takes the opportunity, whilst the peoples hearts were warm with the fresh sense of this great miracle. The brook Kishon — That their blood might be poured into that river, and thence conveyed into the sea, and might not defile the holy land. Slew them — As these idolatrous priests were manifestly under a sentence of death, passed upon such by the sovereign Lord of life and death, so Elijah had authority to execute it, being a prophet, and an extraordinary minister of God's vengeance. The four hundred prophets of the groves, it seems, did not attend, and so escaped, which perhaps Ahab rejoiced in. But it proved, they were reserved to be the instruments of his destruction, by encouraging him to go up to Ramoth — Gilead.