Charles Ellicott Commentary 2 Chronicles 18:7

"And the king of Israel said unto Jehoshaphat, There is yet one man by whom we may inquire of Jehovah: but I hate him; for he never prophesieth good concerning me, but always evil: the same is Micaiah the son of Imla. And Jehoshaphat said, Let not the king say so." — 2 Chronicles 18:7 (ASV)

He never prophesied good to me, but always evil. —Literally, He is not prophesying to me for good, but all his days for evil. Kings: “He prophesieth not to me good but evil.” The chronicler has aggravated the idea of opposition, by adding “all his days;” i.e., throughout his prophetic career. (Compare Homer, Iliad, i. 106.)

Micaiah. —Hebrew, Mîkâyĕhû, which presupposes an older Mîkăyăhû (“Who like Iahu?”). Iahu is in all probability the oldest form of the Divine Name, Iah being an abridgment of it. Syriac and Arabic, “Micah”—the form in 2 Chronicles 18:14 (Hebrew).

Imla. — He is full, or, he fills; etymologically right.

Let not the king say so. —Jehoshaphat hears in the words a presentiment of evil, and deprecates the omen.