Albert Barnes Commentary 1 Kings 22:9

"Then the king of Israel called an officer, and said, Fetch quickly Micaiah the son of Imlah." — 1 Kings 22:9 (ASV)

An officer — More properly, as in the margin, “a eunuch.” Eunuchs seem to have been first introduced among the Israelites by David (1 Chronicles 28:1, note). They were a natural accompaniment of Solomon’s seraglio. The present passage is the first that shows that after the separation of the kingdom, the kings of Israel employed them (Compare 2 Kings 8:6; 2 Kings 9:32).