"Ephod" in the Old Testament refers to two different things. One is the garment worn by the high priest. The other usage of "ephod" seems to refer to a transportable idol.
What is the ephod in the Old Testament?
As part of the high priest's garments, the ephod would be made of fine, twisted linen that was blue, purple, and scarlet colored, and embroidered with gold thread (Exodus 28:4; 29:5; 39:2; Leviticus 8:7). A similar girdle held the ephod together by being draped over the shoulders, crossed, and held together in the back. Two golden rings were attached to the front of the ensemble to hold the breastplate.
A different type of ephod is described in Judges 8:26–27 where Gideon melted down 1,700 shekels worth of gold earrings from the Midianites to make some sort of symbol. We are told that the Israelites worshiped it "… and it became a snare to Gideon and to his family" (Judges 8:27). Later, in Judges 17:5, Micah also made what is called an ephod and teraphim for his sanctuary.
The ephod for the high priest was a garment instructed to be made by God. The ephods in Judges were used in ungodly idol worship. Some scholars think that the idol was clothed in a linen garment and the word "ephod" gradually transitioned to refer to the idol as a whole.
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