Deuteronomy 33:8

“of Levi he said--The burden of this blessing is the appointment of the Levites to the dignified and sacred office of the priesthood (Lev 10:11; Deu 22:8; Deu 17:8-11), a reward for their zeal in supporting the cause of God, and their unsparing severity in chastising even their nearest and dearest relatives who had participated in the idolatry of the molten calf (Exo 32:25-28; compare Mal 2:4-6).”

“Thy holy one - i. e., Levi, regarded as the representative of the whole priestly and Levitical stock which sprang from him. The contrast between the tone of this passage and that of Genesis 49:5-7 is remarkable. Though the prediction of Jacob respecting the dispersion of this tribe held good, yet it was so overruled as to issue in honor and reward. The recovery of God’s favor is to be traced to the faithfulness with which Moses and Aaron, who came of this tribe, served God in their high offices; and to the zeal and constancy which conspicuous persons of the tribe (e. g. Phinehas, Numbers 25:11 ff), and the whole tribe itself (compare Exodus 32:26), manifested on critical occasions in…”

“Let thy Urim - The Thummim and the Urim, which are thine, O Lord by special institution and consecration, (by which he understands the ephod in which they were put, and the high priesthood, to which they were appropriated, and withal the gifts and graces signified by the Urim and Thummim, and necessary for the discharge of that high - office) shall be with thy holy one, that is, with that priest, whom thou hast consecrated to thyself, and who is holy in a more peculiar manner than all the people were; that is, the priesthood shall be confined to and continued in Aaron's family. Whom thou didst prove - Altho' thou didst try him, and rebuke him, yet thou didst not take away the priesthood from…”

“33:8 Levi was Jacob’s third son by Leah (Gen 29:34). The Levites, particularly those descended from Aaron, were entrusted with the priesthood (see Exod 28:1; 32:29; Num 3:9). • Thummim and Urim were precious stones embedded in or suspended from the breastpiece of the ephod, a garment worn by the chief priest. These stones could be consulted to determine God’s will. Their names may be translated “perfections” and “lights,” respectively (see study note on Exod 28:30). • Massah means “[place of] testing,” referring to an incident when the people ran out of water and tested the Lord (see study note on Deut 6:16; Exod 17:1-7). • Meribah means “[place of] contention,” referring to another occasion…”

“Let thy: Exo 28:30, Exo 28:36; Lev 8:8; Num 27:21; Sa1 28:6; Ezr 2:63; Neh 7:65 with thy: Lev 21:7; Num 16:5; Ch2 23:6; Ezr 8:28; Psa 16:10, Psa 106:16; Heb 7:26; Rev 3:7 prove at: Deu 8:2, Deu 8:3, Deu 8:16; Exo 17:7; Num 20:13; Psa 81:7 Deuteronomy 33:9”

“Levi. - Deu 33:8, Deu 33:9. "Thy right and Thy light is to Thy godly man, whom Thou didst prove in Massah, and didst strive with him at the water of strife; who says to his father and his mother, I see him not; and does not regard his brethren, and does not know his sons: for they observed Thy word, and kept Thy covenant." This blessing is also addressed to God as a prayer. The Urim and Thummim - that pledge, which the high priest wore upon his breast-plate, that the Lord would always give His people light to preserve His endangered right (vid., Exo 28:29-30), \- are here regarded as a prerogative of the whole of the tribe of Levi. Thummim is placed before Urim, to indicate at the outset…”