Charles Ellicott Commentary Zechariah 13:2

"And it shall come to pass in that day, saith Jehovah of hosts, that I will cut off the names of the idols out of the land, and they shall no more be remembered; and also I will cause the prophets and the unclean spirit to pass out of the land." — Zechariah 13:2 (ASV)

Unclean spirit. —This is the only passage in the Old Testament in which we find the expression “unclean spirit,” which is of such frequent occurrence in the New. (See on Zechariah 10:2.)