And thou shalt put in the breastplate of judgment the {n} Urim and the Thummim; and they shall be upon Aaron's heart, when he goeth in before the LORD: and Aaron shall bear the judgment of the children of Israel upon his heart before the LORD continually.

(n) Urim signifies light, and thummim perfection: declaring that the stones of the breastplate were most clear, and of perfect beauty: by urim also is meant knowledge, and thummim holiness, showing what virtues are required in the priests.

Wesley's Notes

28:30 The Urim and Thummim - By which the will of God was made known in doubtful cases, was put in this breast - plate, which is therefore called the breast - plate of judgment. Urim and Thummim signify light and integrity: many conjectures there are among the learned what they were: we have no reason to think they were any thing that Moses was to make, more than what was before ordered; so that either God made them himself, and gave them to Moses, for him to put into the breast - plate when other things were prepared; or, no more is meant but a declaration of the farther use of what was already ordered to be made. The words may be read thus, And thou shalt give, or add, to the breast - plate of judgment, the illuminations and perfections, and they shall be upon the heart of Aaron - That is, he shall be endued with a power of knowing and making known the mind of God in all difficult cases relating either to the civil or ecclesiastical state. Their government was a theocracy; God was their king, the high priest was, under God, their ruler, this Urim and Thummim were his cabinet council: probably Moses wrote upon the breast - plate, or wove into it, these words, Urim and Thummim, to signify, that the high - priest, having on him this breast - plate, and asking council of God in any emergency, should be directed to those measures, which God would own. If he were standing before the ark, probably he received instructions from off the mercy - seat, as Moses did, Ex 25:22. If he were at a distance from the ark, as Abiathar was when he enquired of the Lord for David, 1Sam 23:6, then the answer was given either by a voice from heaven, or by an impulse upon the mind of the high priest, which last is perhaps intimated in that expression, he shall bear the judgment of the children of Israel upon his heart. This oracle was of great use to Israel, Joshua consulted it. Num 27:21, and it is likely, the judges after him. It was lost in the captivity, and never retrieved after. It was a shadow of good things to come, and the substance is Christ. He is our oracle; by him God in these last days, makes known himself and his mind to us. Divine revelation centers in him, and comes to us through him; he is the light, the true light, the faithful witness; and from him we receive the Spirit of truth, who leads into all truth. The joining of the breast - plate to the ephod notes, that his prophetical office was founded on his priesthood; and it was by the merit of his death that he purchased this honour for himself, and this favour for us. It was the Lamb that had been slain that was worthy to take the book and to open the seals. Rev 5:9. The judgment - The breast - plate of judgment: That breast - plate which declared the judgment or mind of God to the Israelites.

Scofield Reference Notes

[1] Urim and Thummim

Urim and Thummim, meaning "lights and perfections." Some make these to be simply a collective name for the stones of the breastplate, so that the total effect of the twelve stones is to manifest the "lights and perfections" of Him who is the antitype of the Aaronic high priest. Per contra, Lev 8:8. This would seem to be conclusive that "the Urim and Thummim" are additional to the stones of the breastplate. In use the Urim and Thummim were connected, in some way not clearly expressed, with the ascertainment of the divine will in particular cases Num 27:21 Dt 33:8 1Sam 28:6 Ezra 2:63.

Jamieson-Fausset-Brown Bible Commentary

30. thou shalt put in the breastplate of judgment the Urim and Thummim-The words signify "lights" and "perfections"; and nothing more is meant than the precious stones of the breastplate already described (compare Ex 39:8-21; Le 8:8). They received the name because the bearing of them qualified the high priest to consult the divine oracle on all public or national emergencies, by going into the holy place-standing close before the veil and putting his hand upon the Urim and Thummim, he conveyed a petition from the people and asked counsel of God, who, as the Sovereign of Israel, gave response from the midst of His glory. Little, however, is known about them. But it may be remarked that Egyptian judges wore on the breast of their official robes a representation of Justice, and the high priest in Israel long officiated also as a judge; so that some think the Urim and Thummim had a reference to his judicial functions.

Matthew Henry's Concise Commentary

28:15-30 The chief ornament of the high priest, was the breastplate, a rich piece of cloth, curiously worked. The name of each tribe was graven in a precious stone, fixed in the breastplate, to signify how precious, in God's sight, believers are, and how honourable. How small and poor soever the tribe was, it was as a precious stone in the breastplate of the high priest; thus are all the saints dear to Christ, however men esteem them. The high priest had the names of the tribes, both on his shoulders and on his breast, which reminds us of the power and the love with which our Lord Jesus pleads for those that are his. He not only bears them up in his arms with almighty strength, but he carries them in his bosom with tender affection. What comfort is this to us in all our addresses to God! The Urim and Thummim, by which the will of God was made known in doubtful cases, were put in this breastplate. Urim and Thummim signify light and integrity. There are many conjectures what these were; the most probable opinion seems to be, that they were the twelve precious stones in the high priest's breastplate. Now, Christ is our Oracle. By him God, in these last days, makes known himself and his mind to us, Heb 1:1,2; Joh 1:18. He is the true Light, the faithful Witness, the Truth itself, and from him we receive the Spirit of Truth, who leads into all truth.