Exodus 28:29-30

29So Aaron shall carry the names of the sons of Israel (Jacob) in the breastpiece of judgment over his heart when he enters the Holy Place, to bring them in continual remembrance before the Lord.

30In the breastpiece of judgment you shall put the Urim (Lights) and the Thummim (Perfections) [to be used for determining God’s will in a matter]. They shall be over Aaron’s heart whenever he goes before the Lord, and Aaron shall always carry the judgment (verdict, judicial decisions) of the sons of Israel over his heart before the Lord.