Rashi on Deuteronomy 33:2/רש"י על דברים ל״ג:ב׳

1ויאמר ה' מסיני בא AND HE SAID, THE LORD CAME FROM SINAI — First he began with praise of the Omnipresent, and only afterwards did he begin with what concerned Israel; but in the praise of God with which he began there is also mention of Israel’s merit. All this was by way of intercession, as though to say, “These are worthy that blessing should rest upon them” (Sifrei Devarim 343:1).

2מסיני בא [THE LORD] CAME FROM SINAI — He went forth towards them when they were about to take their stand at the foot of the Mount, — as a bridegroom goes forth to welcome his bride, as it is said, (Exodus 19:17) “And Moses brought the people forth to meet God”: this teaches us that He (God) was Himself going forth facing them (cf. Mekhilta and Rashi on the verse quoted).

3וזרח משעיר למו AND HE SHONE FORTH FROM SEIR UNTO THEM (the Israelites), because He first addressed Himself to the sons of Esau (the inhabitants of Seir) that they should accept the Law, but they refused,

4הופיע מהר פארן HE APPEARED FROM MOUNT PARAN, because He went there and addressed Himself to the sons of Ishmael (who dwelt in Paran, see Genesis 21:21) that they should accept it and they also refused (Sifrei Devarim 343:6; Avodah Zarah 2b),

5ואתה AND HE CAME therefore to Israel,

6מרבבת קדש — i.e. and with Him were a part of the myriads of the holy angels, and not all of them and not even the majority of them: not as is the way of a human being who displays all the splendour of his riches and magnificence on his marriage day (Sifrei Devarim 343:11).

7אשדת (lit., “fire, Law”, or “fire of Law”) — i.e. the Law which had been written before Him from olden times in black fire upon white fire (Midrash Tanchuma, Bereshit 1). The meaning of the verse is: He gave to them (למו) upon the Tablets the writing of His right hand (cf. Talmud Yerushalmi Shekalim 9:1). Another explanation of אש דת: Understand this as the Targum has it: a law which was given them from the midst of the fire (cf. Exodus 19:18).