The Angel on Mount Sinai
The passage in Acts which refers to Moses’ encounter with the angel at the burning bush contains another reference to a contact between Moses and God.
"This is the one who was in the congregation in the wilderness with the angel who spoke to him at Mount Sinai, and with our fathers. He received living oracles to give to us." (Acts 7:38)
The occasion where God spoke to Moses and the Israelites in the desert at Mount Sinai is the occasion where Moses received the Law. Acts is quite clear that the law was delivered through an angel. Nevertheless, when one reads the words that the angel delivered it is clear that God is speaking through the angel.
"And God spoke all these words, saying, 'I am the LORD your God, who brought you out of the land of Egypt, out of the house of slavery. You shall have no other gods before me.'" (Exodus 20:1-3)
The words here are clearly the words of God. They command that no-one should follow any other god. Nevertheless they are delivered on God’s behalf by an angel who represents God.
There is a reference to this kind of thing in the book of Exodus:
"Behold, I send an angel before you to guard you on the way and to bring you to the place that I have prepared. Pay careful attention to him and obey his voice; do not rebel against him, for he will not pardon your transgression, for my name is in him." (Exodus 23:20,21)
This passage refers to the angel as carrying the name of God.