Deuteronomy 33:8-10

8 And of Levi he said, "Give to Levi thy Thummim, and thy Urim to thy godly one, whom thou didst test at Massah, with whom thou didst strive at the waters of Mer'ibah;
9 who said of his father and mother, 'I regard them not'; he disowned his brothers, and ignored his children. For they observed thy word, and kept thy covenant.
10 They shall teach Jacob thy ordinances, and Israel thy law; they shall put incense before thee, and whole burnt offering upon thy altar.