Deuteronomy 33:8 Kabbalah

וּלְלֵוִ֣י אָמַ֔ר תֻּמֶּ֥יךָ וְאוּרֶ֖יךָ לְאִ֣ישׁ חֲסִידֶ֑ךָ אֲשֶׁ֤ר נִסִּיתוֹ֙ בְּמַסָּ֔ה תְּרִיבֵ֖הוּ עַל־מֵ֥י מְרִיבָֽה׃

And of Levi he said: Thy Thummim and Thy Urim be with Thy holy one, Whom Thou didst prove at Massah, With whom Thou didst strive at the waters of Meribah;

Read kabbalistic (mystical) interpretation of Deuteronomy 33:8: and classical mystical sources.