Parallel
Deuteronomy 33:5
Rahlfs Septuagint (1935) · Berean Standard Bible
καὶ ἔσται ἐν τῷ ἠγαπημένῳ ἄρχων συναχθέντων ἀρχόντων λαῶν ἅμα φυλαῖς Ισραηλ
So the LORD became King in Jeshurun (note: Jeshurun means the upright one, a term of endearment for Israel; also in verse 26.) when the leaders of the people gathered, when the tribes of Israel came together.