God spoke the words of the Ten Commandments the first time. The people did not want to listen to the voice of God. They instead heard thunder and saw lightning and smoke. A similar thing happened with Jesus.
John 12:28-29
Father, glorify your name!" Then a voice came from heaven, "I have glorified it, and will glorify it again."The crowd that was there and heard it said it had thundered; others said an angel had spoken to him.

Who is this "angel" God sent to go with them who has the power to forgive sin?
1 Cor 10:1-4
For I do not want you to be ignorant of the fact, brothers, that our forefathers were all under the cloud and that they all passed through the sea.They were all baptized into Moses in the cloud and in the sea. They all ate the same spiritual foodand drank the same spiritual drink; for they drank from the spiritual rock that accompanied them, and that rock was Christ.

John 5:22
Moreover, the Father judges no one, but has entrusted all judgment to the Son

Pretty clear...the "angel", God's Presence, was God, the Son.

Another example of how God, the Son interacted with people in the Old Testament is found in this passage.
Exod 24:9-11
Moses and Aaron, Nadab and Abihu, and the seventy elders of Israel went up and saw the God of Israel. Under his feet was something like a pavement made of sapphire, clear as the sky itself. But God did not raise his hand against these leaders of the Israelites; they saw God, and they ate and drank.

And then we have this verse.
John 6:46
No one has seen the Father except the one who is from God; only he has seen the Father.

If no one can see the Father then how can Moses, Aaron, Nadab, and Abihu, along with the seventy elders see God? Again, it's perfectly clear... the leaders saw God, the Son.