Acts 1:1-4

1 The first book I wrote, Theophilus, concerned all that Jesus began both to do and to teach,  2 until the day in which he was received up, after he had given commandment through the Holy Spirit to the apostles whom he had chosen.  3 To these he also showed himself alive after he suffered, by many proofs, appearing to them over a period of forty days, and speaking about God's Kingdom.  4 Being assembled together with them, he charged them, “Don't depart from Jerusalem, but wait for the promise of the Father, which you heard from me.