Albert Barnes Commentary Deuteronomy 33:2

"And he said, Jehovah came from Sinai, And rose from Seir unto them; He shined forth from mount Paran, And he came from the ten thousands of holy ones: At his right hand was a fiery law for them." — Deuteronomy 33:2 (ASV)

By “Seir” is understood the mountain-land of the Edomites, and by “Mount Paran” the range that forms the northern boundary of the desert of Sinai (see note). Thus, the verse forms a poetical description of the vast arena on which the glorious manifestation of the Lord in the giving of the covenant took place.

With ten thousands of saints — Render as: from among ten thousands of holy ones (literally, from myriads of holiness, that is, holy Angels) . God is represented as leaving heaven, where He dwells among the host of the Angels (1 Kings 22:19), and descending in majesty to earth (Micah 1:3).

A fiery law — or, more literally, as noted in the margin, perhaps with an allusion to the pillar of fire (Exodus 13:21). The word is much disputed.