Introduction. The writer refers to his former treatise, intimating rather than stating that he is beginning a second. The Ascension is his present starting-point, but instead of simply referring to the account already given (Luke 24:50-53), he narrates it again, and in a way which shows that the tradition had grown considerably in the interval. The apostles appear as a fixed number, with definite functions. The text reads more simply without Acts 1:3; the things concerning the kingdom of God is the writer's summary of the contents of Christian preaching; cf. Acts 8:12, Acts 19:8; Acts 28:23; Acts 28:30. It is nowhere explained. The forty days are heard of only here in NT: they provide room for the growing tradition of a life of Christ on earth after the Resurrection.
Acts 1:2 seems to place the choice of the apostles in this period, as well as the instructions which Jesus gave them through the Holy Spirit, but there is no real conflict with Luke 6:13.
Acts 1:4. The writer silently glides into the narrative of the second treatise. We are told of a meeting or a meal (mg., see Field, Notes on Trans. of NT, p. 110) of Jesus with the disciples, at which He prescribed their future policy. They are to stay at Jerusalem till the promise of the Father (Luke 24:49) is fulfilled and the Spirit comes to them. (In the Acts of Peter their stay is fixed at twelve years.) The prediction of John the Baptist was that Jesus Himself would baptize with Holy Spirit; here the imparting of the Spirit is made to mean the speedy clothing of the disciples with power (Acts 1:8; cf. Acts 2:6-11).