Galatians 3:19
What then is [the benefit of] the law of Moses? It was introduced [as part of God's revelation] in order to define what sin was, until the seed [i.e., Jesus] would come, to whom the promise [of never ending life] was made. The law of Moses was ordained through [the medium of] angels and [delivered] through the hand of an intermediary [i.e., Moses].
Acts 7:38
This is the man who was with our forefathers and with the assembly [of Hebrews] in the wilderness [after] the angel had spoken to him at Mt. Sinai. He [is the one] who received the living messages [from God at Mt. Sinai] and gave them to us.
Hebrews 12:19
to the blast of a trumpet and the sound of words [from God] that the hearers begged not to have to listen to [anymore]. [See Ex. 20:19].