Exodus 19:20
19 When the sound of the horn grew louder and louder, Moses was speaking and God was answering him with a voice. 20 The Lord came down on Mount Sinai, on the top of the mountain, and the Lord summoned Moses to the top of the mountain, and Moses went up. 21 The Lord said to Moses, “Go down and solemnly warn the people, lest they force their way through to the Lord to look, and many of them perish.
Deuteronomy 4:36
35 You have been taught that the Lord alone is God—there is no other besides him. 36 From heaven he spoke to you in order to teach you, and on earth he showed you his great fire from which you also heard his words. 37 Moreover, because he loved your ancestors, he chose their descendants who followed them and personally brought you out of Egypt with his great power
Nehemiah 9:13
12 You guided them with a pillar of cloud by day and with a pillar of fire by night to illumine for them the path they were to travel. 13 “You came down on Mount Sinai and spoke with them from heaven. You provided them with just judgments, true laws, and good statutes and commandments. 14 You made known to them your holy Sabbath; you issued commandments, statutes, and laws to them through Moses your servant.
Notes and References
"... At Mt. Sinai, God made His great covenant (an agreement or compact) with Israel, by which they became His special people. For ancient interpreters, this was a most—perhaps the most—significant event in the whole Hebrew Bible. Not only did it establish a unique relationship between one people and the Lord of all, but the laws and commandments that God gave to Israel became a central preoccupation for Jews ever afterward ... But what exactly happened on the day in question? The events themselves appeared elusive. On the one hand, it seemed that God had, as it were, gone down to meet Moses on top of the mountain: the Bible says specifically 'And the Lord went down upon the mountain' (Exodus 19:20) and elsewhere reports that God 'called to him [Moses] from the mountain' (Exodus 19:3). On the other hand, God later says, 'You have seen for yourselves that I have talked with you from heaven' (Exodus 20:21), and still later Moses recalls, 'Out of heaven He caused you to hear His voice' (Deuteronomy 4:36). So where was God really? The book of Nehemiah summed up the paradox ... Nehemiah 9:13 ..."
Kugel, James L. The Bible as it Was (pp. 373-374) Harvard University Press, 1998