Acts 7:56

‘And said, “Behold, I see the heavens opened, and the Son of Man standing on the right hand of God.”

At what he saw he could not help himself, and he cried out and declared his interpretation of what he saw. It revealed that the Son of Man had truly come in the clouds to the throne of God and had received His everlasting dominion and Kingly Rule (Daniel 7:13), and it was in those terms that he expressed it. It was a fulfilment of Jesus promise to His judges in Matthew 26:64. This is the only use of the term Son of Man outside the Gospels, where it is restricted to Jesus using it of Himself, apart from in Revelation 1:13; Revelation 14:14 where it refers to the glorious Son of Man, illustrating both the early nature of the narrative, and its uniqueness. It confirmed that Jesus was the glorious Messiah, having been given all authority in heaven and earth. And He was standing because He was ready to receive His servant. He knew what was coming next. He had experienced something similar Himself.

Some consider that Jesus is standing because He is acting as a witness, as He bears testimony to Stephen before the Father. A witness always had to stand. And we need not doubt that Jesus bore witness to the Godhead of Stephen's triumph. But a welcomer would also stand. And Luke probably intends us to contrast this open welcome by the Lord of glory with the rejection of the Sanhedrin. The prime authority in heaven welcomes Stephen even while the authorities on earth despatch him. And the same will be true for all who are persecuted for bearing witness to His Name.

‘I see the heavens opened.' A way of expressing that he had a glimpse of the Beyond. He was being given a vision of what was usually veiled.