Exodus 19:20

And the Lord revealed Himself on mount Sinai upon the summit of the mountain, and the Lord called unto Mosheh from the summit of the mount, and Mosheh went up.

AND THE ETERNAL CAME DOWN UPON MOUNT SINAI. If you will succeed in having insight into this section [of the Torah], you will understand that His Great Name, [i.e., the Tetragrammaton], came down upon Mount Sinai, and that He abode thereon in fire and spoke to Moses. The communication to Moses in the entire section was by this Proper Name of the Eternal. However, the ascent [of Moses — as mentioned in Verse 3: And Moses went up unto G-d] — and his bringing forth [the people out of the camp — as mentioned in Verse 17] — were towards the place of the Glory, as I have explained. And He warned, lest they break through unto the Eternal to gaze, because even the nobles of the children of Israel did not see Him, and all Israel heard the Voice of G-d out of the midst of the fire. It is this which Scripture says, And ‘Elokim’ (G-d) spoke all these words, just as our Rabbis have said: “Elokim designates the Judge.”) And they have also said [with reference to the first two commandments]: (the Almighty) is analogous to “the Judge.” “We have heard them from Hagvurah (the Almighty Himself).” In Deuteronomy it is written: These words the Eternal spoke unto all your assembly. spoke.” That is because, etc. That is because Scripture explains there [in the same verse] that He spoke out of the midst of the fire., 5:4. And this is the sense of the verse, The Eternal spoke with you face to face in the mount out of the midst of the fire., 5:4. And this is why it is said, I am the Eternal thy G-d., etc.” (Abusaula). The allusion is to the two Divine Names — the Tetragrammaton and Elokim — mentioned together here in 20:2. Now do not find a difficulty in what the people said to Moses, For who is there of all living flesh, that hath heard the Voice of the living G-d speaking out of the midst of the fire? speaking (Abusaula). They did not say “that they heard G-d speaking out of the midst of the fire,” but they said the Voice of G-d, referring to what they perceived. This is why they said, Go thou near, and hear all that the Eternal our G-d may say., Verse 24. And so did Moses say to them, Did ever a people hear the Voice of G-d speaking out of the midst of the fire?, 4:33. The word “speaking” here is referring to “the Voice,” something like the verse, and he heard the Voice speaking unto him.
From this you will understand …