Moses
Deuteronomy 5:4ESV·traditional attribution

The LORD spoke with you face to face at the mountain, out of the midst of the fire,

John Calvin Reformed @genevareformer

4. Face to face. Again he commends the Law by mentioning their certainty about it; for, when God openly manifested Himself, there could be no doubt of the author from whom it proceeded. To speak “face to face,” is equivalent to discoursing openly and familiarly; and in point of fact God had spoken with them, as mortals and friends communicate with each other in their mutual dealings.

Matthew Henry Presbyterian @wholebiblehenry

Here, 1. Moses summons the assembly. He called all Israel; not only the elders, but, it is likely, as many of the people as could come within hearing, Deu 5:1. The greatest of them were not above God's command, nor the meanest of them below his cognizance; but they were all bound to do. 2.

Commenting on Deuteronomy 5:1-5

John Gill Reformed Baptist @doctorgill

I stood between the Lord and you at that time,.... Between the Word of the Lord and you, as the Targums of Onkelos and Jonathan; that is, about that time, not at the exact precise time the ten commandments were delivered, for these were spoken immediately to the people; but when the ceremonial law was given, which was ordained by angels, in the hand of...