Exodus 39:20-22

New American Standard Bible

²⁰ Furthermore, they made two gold rings and placed them on the bottom of the two shoulder pieces of the ephod, on the front of it, close to the place where it joined, above the woven band of the ephod. ²¹ And they bound the breastpiece by its rings to the rings of the ephod with a violet cord, so that it would be on the woven band of the ephod, and that the breastpiece would not come loose from the ephod, just as the Lord had commanded Moses.

^22 (A)Then he made the robe of the ephod of woven work, all of violet;