Levi was Jacob’s third son by Leah (Genesis 29:34). His descendants were called Levites. The Levites, especially those descended from Aaron, were given responsibility for the priesthood (see Exodus 28:1; 32:29; Numbers 3:9).
Thummim … Urim: These were precious stones placed in or attached to the breastpiece of the ephod (a special garment worn by the chief priest). The stones were used to seek God’s will. Their names may mean “perfections” and “lights” (see study note on Exodus 28:30).
Massah means “[place of] testing.” This refers to the time the people ran out of water and tested the Lord (see study note on Deuteronomy 6:16; Exodus 17:1–7).
Meribah means “[place of] contention.” This refers to the time the Israelites argued with the Lord until he provided water from a rock (Numbers 20:13, 24).