11 The former treatise I made, O Theophilus, concerning all that Jesus began both to do and to teach, 2 until the day in which he was received up, after that he had given commandment through the Holy Spirit unto the apostles whom he had chosen: 3 To whom he also showed himself alive after his passion by many proofs, appearing unto them by the space of forty days, and speaking the things concerning the kingdom of God:
Matthew Henry's Commentary on Acts 1:1-3
Commentary on Acts 1:1-5
(Read Acts 1:1-5)
Our Lord told the disciples the work they were to do. The apostles met together at Jerusalem; Christ having ordered them not to depart thence, but to wait for the pouring out of the Holy Spirit. This would be a baptism by the Holy Ghost, giving them power to work miracles, and enlightening and sanctifying their souls. This confirms the Divine promise, and encourages us to depend upon it, that we have heard it from Christ; for in Him all the promises of God are yea and amen.