Before [Jesus] was taken up, he gave instructions by the power of the Holy Spirit to the men he had chosen as his apostles. For forty days after his death he appeared to them many times in ways that proved beyond doubt that he was alive. They saw him, and he talked with them about the Kingdom of God.
And when they came together, he gave them this order: “Do not leave Jerusalem but wait for the gift I told you about, the gift my Father promised. John baptized with water, but in a few days you will be baptized with the Holy Spirit. When the Holy Spirit comes upon you, you will be filled with power, and you will be witnesses for me in Jerusalem, in all of Judea and Samaria, and to the ends of the earth.”
After saying this, he was taken up to heaven as they watched him, and a cloud hid him from their sight.
They still had their eyes fixed on the sky as he went away, when two men dressed in white suddenly stood beside them and said, “Galileans, why are you standing there looking up at the sky? This Jesus, who was taken from you into heaven, will come back in the same way that you saw him go to heaven."