Charles Ellicott Commentary 1 Kings 18:10

"As Jehovah thy God liveth, there is no nation or kingdom, whither my lord hath not sent to seek thee: and when they said, He is not here, he took an oath of the kingdom and nation, that they found thee not." — 1 Kings 18:10 (ASV)

There is no nation. —This unremitting search—implying perhaps some supremacy or authority over neighbouring kingdoms—ill suits the half-hearted enmity of Ahab. No doubt it was the work of Jezebel, in Ahab’s name, connived at (as in the murder of Naboth) by his timidity.