Deuteronomy 33:8

Of Levi he said Said to God in prayer. Let thy Thummim, &c. That is, the Thummim and Urim which are thine, O Lord, by special institution and consecration, (understanding thereby the ephod, in which they were put, the high-priesthood to which they were appropriated, and withal the gifts and graces signified by them, and necessary for the discharge of that high office,) 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 the people are. He means let the family of Aaron perpetually retain the priesthood, and be endued with that uprightness in the discharge of their duty and that light and knowledge in divine things which are signified by the Thummim and Urim. Notwithstanding this blessing, the Urim and Thummim were lost in the captivity, and never restored under the second temple. But they have their full accomplishment in Jesus Christ, God's Holy One, and our great High-Priest, of whom Aaron was but a type. With him, who had lain in the Father's bosom from eternity, the Urim and Thummim shall ever remain, for he is the wonderful and everlasting Counsellor. Whom thou didst prove at Massah That is, try and rebuke, but yet didst not take away the priesthood from him. With whom thou didst strive Whom thou didst reprove and chastise. Le Clerc, however, refers these words to the people. Whom thou, O Israel, didst prove or tempt at Massah, and with whom thou didst strive, &c. Which happened twice. See Exodus 17:2, and Numbers 20:2. In both these places, it appears that Aaron was tempted, and tried, and strove against, by the people no less than Moses.