The rings of the breastpiece shall be tied to the rings of the ephod with a cord of blue yarn, so that the breastpiece is above the waistband of the ephod and does not swing out from the ephod.
Jewish Publication Society of America Version (JPS1917) - Exodus 28:28 >And they shall bind the breastplate by the rings thereof unto the rings of the ephod with a thread of blue, that it may be upon the skilfully woven band of the ephod, and that the breastplate be not loosed from the ephod.