Atos 1:3

3. Showed himself alive Gloriously and repeatedly displayed himself in his resurrection nature.

Infallible proofs As Christ is the great miracle, so in him the resurrection is the central miracle apparent to men; and it was important, therefore, that this miracle should be sustained by infallible proofs. The evangelists record nine appearances of Jesus. In regard to Jesus’ risen body, see note on Luke 24:36.

Forty days Compare note on Luke 24:44-45.

Between the Passover (when Christ was crucified) and the Pentecost were, inclusive, fifty days; during forty of which the various showings of himself took place, and the remaining ten days were the those days of Acts 1:15. Forty, seventy, and one hundred and twenty are the three primal sacred numbers multiplied by the decimal. See on Acts 1:15. Forty days according to Wordsworth, on this passage, is the period indicating “a probation before some great event;” that is, the completion of some preparatory stage. Such was the fact with Moses before the giving of the law, Exodus 24:18; Exodus 34:28; Deuteronomy 9:9; Deuteronomy 10:10; with Hebrew spies, Numbers 13:25; Numbers 14:34; with Elias, 1 Kings 19:8; with Nineveh, Jonah 3:4. And as the purification by the presentation of a male child in the temple required a period of forty days, so forty days was Jesus’ probation before he was presented, Luke 2:22; forty days his probationary temptation, Mark 1:13; and forty days his earthly resurrection stage before ascension. And this last forty days were the apostolic probation before the Pentecostal preparatories commenced.

Things pertaining Doubtless fully and clearly as their advancement in knowledge allowed, yet not so successfully but that they asked the unwise question in Acts 1:6.

Kingdom of God Not that a large body of new teachings was given, but the kingdom of God was the topic of all he did say.