“To whom also he shewed himself alive after his passion by many infallible proofs, being seen of them forty days, and speaking of the things pertaining to the kingdom of God:”
King James Version (KJV)
Matthew Henry's Concise Commentary
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.
“But this is that which was spoken by the prophet Joel;”