John Gill Commentary Deuteronomy 5:28

"And Jehovah heard the voice of your words, when ye spake unto me; and Jehovah said unto me, I have heard the voice of the words of this people, which they have spoken unto thee: they have well said all that they have spoken." — Deuteronomy 5:28 (ASV)

And the Lord heard the voice of your word, when you spoke to
me
Not only in a general way, as he hears and knows all that is spoken by men; for there is not a word on the tongue, formed upon it, and uttered by it, but what is altogether known to him; but in a special and particular manner observed, took notice of, approved, and was well pleased with what these people said:

and the Lord said to me, I have heard the voice of the words of this
people which they have spoken to you ;
not only heard the sound of them, but took notice of the sense and meaning of them, and listened to them with pleasure and delight:

they have well said all that they have spoken ;
expressing such an awe and reverence of the divine Majesty, desiring to have a mediator between God and them, and purposing and promising to hearken to and obey whatsoever he should command by him.