Exodus 39:20-22

Amplified Bible

²⁰ Furthermore, they made two [other] gold rings and attached them to the bottom of the two shoulder pieces of the ephod, at the front of it, close to the place where it is joined, above the woven sash of the ephod. ²¹ They bound the breastpiece by its rings to the rings of the ephod with a blue cord, so that it would lie on the woven sash of the ephod, and so that the breastpiece would not come loose from the ephod, just as the Lord commanded Moses.

²² Then Bezalel made the robe of the ephod of woven work, all of blue;