Then I looked up and saw four horns.
References for Zechariah 1:18
I said to the messenger speaking with me, "What are these?" He said to me, "These are the horns that scattered Judah, Israel, and Jerusalem."
Then the LORD showed me four metalworkers.
I said, "What are they coming to do?" And he said, "These are the horns that scattered Judah so that no one could raise his head. The metalworkers have come to terrify them and to destroy the horns of the nations, those who were attacking the land of Judah with their horns to scatter it."
References for Zechariah 1:21