“Insert the Urim and Thummim into the sacred chestpiece so they will be carried over Aaron’s heart when he goes into the Lord’s presence. In this way, Aaron will always carry over his heart the objects used to determine the Lord’s will for his people whenever he goes in before the Lord.” (Exodus 28:30, NLT).
One of the primary priestly functions was to determine God’s will for His people. The priest’s chestpiece provided a container for the Urim and Thummim.The Hebrew words descibing the chestpiece literally meant “chestpiece for decision.”