3 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:
English Standard Version
3 He presented himself alive to them after his suffering by many proofs, appearing to them during forty days and speaking about the kingdom of God.
3 After his death, he presented himself alive to them in many different settings over a period of forty days. In face-to-face meetings, he talked to them about things concerning the kingdom of God.
New King James Version
3 to whom He also presented Himself alive after His suffering by many infallible proofs, being seen by them during forty days and speaking of the things pertaining to the kingdom of God.
New Living Translation
3 During the forty days after he suffered and died, he appeared to the apostles from time to time, and he proved to them in many ways that he was actually alive. And he talked to them about the Kingdom of God.
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.