The Urim and Thummim were sacred stones used by the High Priest of Israel to seek divine guidance. According to the Bible, these stones were placed in the breastplate of the high priest and were used in the Tabernacle and later in the Temple.
When the high priest asked a question, he would place the Urim and Thummim in the Ark of the Covenant and consult them. The stones would then fall into one of four cups, each representing a different response: "It is certain," "It is not certain," "Ask again later," or "Reply hazy, try again."
The Urim and Thummim were a symbol of God's presence and authority, and their use was a sacred ritual that required great reverence and proper procedure.