In Exodus 28 the Bible tells about a pair objects carried by the high priest of Israel. These mysterious things were called the Urim and the Thummim. The high priest of Israel wore a breastplate that held twelve stones, each one representing a tribe of Israel. Also in the breastplate were the Urim and Thummim. God gave direction to Israel through the Urim and Thummim, but the Bible gives no specifics about what they were or how they were used.
Some ancient Jewish records suggest they glowed (like the Sankara stones in Indiana Jones and the Temple of Doom). Others have suggested they were stones with Hebrew letters that spelled out words. No one knows for sure. Some think they were stones, others sticks and others jewels. No one knows what they were made of. The Bible mentions their use a couple times but only in general terms. The most likely possibility is that they were used like lots to determine yes or no answers or to decide between two choices.
Regardless of how they were used, the Urim and Thummim revealed to the leaders of Israel the the will of God. In 1 Samuel 28:6 we are told that God did not answer Saul’s prayer for direction about an army of Philistines. God did not answer, “by dreams, nor by Urim, nor by prophets.” The only specific instruction about the use of these devices is found in Numbers 27:20. When Joshua succeeded Moses as leader of the Israelites he was to go before the high priest. The Lord would give direction to Joshua through the Urim and Thummim. “And he shall stand before Eleazar the priest, who shall ask counsel for him after the judgment of Urim before the LORD: at his word shall they go out, and at his word they shall come in, both he, and all the children of Israel with him, even all the congregation.” (Numbers 27:21)
One other passage seems to show how the Urim and Thummim were used. In 1 Samuel 23 David is accompanied by a priest while he flees from Saul. David sought the Lord’s direction and, possibly through the Urim and Thummim, learned whether he should attack the Philistines, if Saul would come after him, and if the people of Keilah would betray him. God gave guidance to David through the ministry of the priest and the Urim and Thummim.
After 1 Samuel there is no other reference to the Urim being used. From the last years of Saul’s reign to the end of the Babylonian captivity the Bible makes no mention of the Urim and Thummim. Ezra and Nehemiah contain brief references to these things as part of the return of the high priest of Israel. After that the Bible is completely silent. The increased ministry of the prophets during the days of the kings appears to have ended Israel’s dependence on the Urim and Thummim to find the will of God. With the close of the Old Testament period God no longer reveals His will through the Urim and Thummim.