Exodus 28:28

The rings of the breastpiece are to be tied to the rings of the ephod with blue cord, connecting it to the waistband, so that the breastpiece will not swing out from the ephod.

(New International Version)

'They shall bind the breastpiece by its rings to the rings of the ephod with a blue cord, so that it will be on the skillfully woven band of the ephod, and that the breastpiece will not come loose from the ephod.

(New American Standard Bible)

And they shall bind the breastplate by the rings thereof unto the rings of the ephod with a lace of blue, that it may be above the curious girdle of the ephod, and that the breastplate be not loosed from the ephod.

(King James Version)