Acts 1:1-5 - The Preface
1 In the first book, O Theophilus, I wrote about all that Jesus began to do and to teach, 2 until the day when he was taken up to heaven, after he had given orders through the Holy Spirit to the apostles whom he had chosen. 3 To these he also presented himself alive after his suffering, by many convincing proofs, appearing to them over a period of forty days and speaking of the things concerning the kingdom of God.
4 And while staying with them, he commanded them not to leave Jerusalem, but to wait for what the Father had promised, "Which," he said, "you heard of from me; 5 for John baptized with water, but before many days you will be baptized with the Holy Spirit."