Angels were involved in the giving of the law

Acts 7:53 you who have received the law that was given through angels but have not obeyed it.

Galatians 3:19 Why, then, was the law given at all? It was added because of transgressions until the Seed to whom the promise referred had come. The law was given through angels and entrusted to a mediator.

Hebrews 2:2 For since the message spoken through angels was binding, and every violation and disobedience received its just punishment, ...

Deuteronomy 33:2 He said: "The LORD came from Sinai and dawned over them from Seir; he shone forth from Mount Paran. He came with myriads of holy ones from the south, from his mountain slopes.
Psalm 68:17 The chariots of God are tens of thousands and thousands of thousands; the Lord has come from Sinai into his sanctuary.

Matthew Henry comments on Acts 7:53 that the law is said to be received by the disposition of angels, because angels were employed in the solemnity of giving the law, in the thunderings and lightnings, and the sound of the trumpet. It is said to be ordained by angels (Gal. 3:19 ), God is said to come with ten thousand of his saints to give the law (Deu. 33:2 ), and it was a word spoken by angels, Heb. 2:2 . This put an honour both upon the law and the Lawgiver, and should increase our veneration for both. But those that thus received the law yet kept it not, but by making the golden calf broke it immediately in a capital instance.

Barnes notes that the phrase given through angels has been supposed to mean that the Law was given “amidst” the various ranks of angels, being present to witness its promulgation. Others suppose that the angels were employed as agents or instruments to communicate the Law. All that the expression fairly implies is that the Law was given amidst the attending ranks of angels, as if they were summoned to witness the pomp and ceremony of giving “law” to an entire people, and through them to an entire world. It should be added, moreover, that the Jews applied the word “angels” to any messengers of God; to fire, and tempest, and wind, etc. And all that Stephen means here may be to express the common Jewish opinion that God was attended on this occasion by the heavenly hosts, and by the symbols of his presence, fire, and smoke, and tempest.