Exodus 28:30

28:30 “You are to put the Urim and the Thummim ¹  into the breastpiece of decision; and they are to be over Aaron’s heart when he goes in before the Lord. Aaron is to bear the decisions ²  of the Israelites over his heart before the Lord continually.

Exodus 29:20

29:20 and you are to kill the ram and take some of its blood and put it on the tip of the right ear of Aaron, on the tip of the right ear of his sons, on the thumb of their right hand, and on the big toe of their right foot, ³  and then splash the blood all around on the altar.

[28:30]  ¹ sn The Urim and the Thummim were two objects intended for determining the divine will. There is no clear evidence of their size or shape or the material of which they were made, but they seem to have been familiar items to Moses and the people. The best example of their use comes from 1 Sam 14:36-42. Some have suggested from the etymologies that they were light and dark objects respectively, perhaps stones or sticks or some other object. They seem to have fallen out of use after the Davidic period when the prophetic oracles became popular. It may be that the title “breastpiece of judgment” indicates that these objects were used for making “decisions” (J. P. Hyatt, Exodus [NCBC], 283-84). U. Cassuto has the most thorough treatment of the subject (Exodus, 378-82); he lists several very clear rules for their uses gathered from their instances in the Bible, including that they were a form of sacred lot, that priests or leaders of the people only could use them, and that they were used for discovering the divine will in areas that were beyond human knowledge.

[28:30]  ² tn Or “judgment” (KJV, ASV, NASB, NRSV). The term is מִשְׁפָּט (mishpat), the same word that describes the breastpiece that held the two objects. Here it is translated “decisions” since the Urim and Thummim contained in the breastpiece represented the means by which the Lord made decisions for the Israelites. The high priest bore the responsibility of discerning the divine will on matters of national importance.

[29:20]  ³ sn By this ritual the priests were set apart completely to the service of God. The ear represented the organ of hearing (as in “ears you have dug” in Ps 40 or “awakens my ear” in Isa 50), and this had to be set apart to God so that they could hear the Word of God. The thumb and the hand represented the instrument to be used for all ministry, and so everything that they “put their hand to” had to be dedicated to God and appropriate for his service. The toe set the foot apart to God, meaning that the walk of the priest had to be consecrated – where he went, how he conducted himself, what life he lived, all belonged to God now.