Exodus 39:20

And they made two rings of gold, and put them on the two ends of the breastplate, upon the border of it, which was on the side of the ephod inward.

And they did bind the breastplate by his rings unto the rings of the ephod with a lace of blue, that it might be above the curious girdle of the ephod, and that the breastplate might not be loosed from the ephod; as the LORD commanded Moses.