Jesus appeared to the apostles after his resurrection, teaching them about the kingdom of God for 40 days, and instructed them to wait in Jerusalem for the Holy Spirit. The apostles asked Jesus if he would restore the kingdom of Israel, but he told them it was not for them to know the times or moments set by the Father. Jesus then ascended into heaven, and the apostles returned to Jerusalem, where they prayed and chose a replacement for Judas, Matthias, through a process of prayer and casting lots.
1 Certainly, O Theophilus, I composed the first discourse about everything that Jesus began to do and to teach 2 instructing the Apostles, whom he had chosen through the Holy Spirit, even until the day on which he was taken up 3 He also presented himself alive to them, after his Passion, appearing to them throughout forty days and speaking about the kingdom of God with many elucidations 4 And dining with them, he instructed them that they should not depart from Jerusalem, but that they should wait for the Promise of the Father, "about which you have heard," he said, "from my own mouth 5 For John, indeed, baptized with water, but you shall be baptized with the Holy Spirit, not many days from now. 6 Therefore, those who had assembled together questioned him, saying, "Lord, is this the time when you will restore the kingdom of Israel? 7 But he said to them: "It is not yours to know the times or the moments, which the Father has set by his own authority 8 But you shall receive the power of the Holy Spirit, passing over you, and you shall be witnesses for me in Jerusalem, and in all Judea and Samaria, and even to the ends of the earth. 9 And when he had said these things, while they were watching, he was lifted up, and a cloud took him from their sight 10 And while they were watching him going up to heaven, behold, two men stood near them in white vestments 11 And they said: "Men of Galilee, why do you stand here looking up toward heaven? This Jesus, who has been taken up from you into heaven, shall return in just the same way that you have seen him going up to heaven. 12 Then they returned to Jerusalem from the mountain, which is called Olivet, which is next to Jerusalem, within a Sabbath day’s journey 13 And when they had entered into the cenacle, they ascended to the place where Peter and John, James and Andrew, Philip and Thomas, Bartholomew and Matthew, James of Alphaeus and Simon the Zealot, and Jude of James, were staying 14 All these were persevering with one accord in prayer with the women, and with Mary, the mother of Jesus, and with his brothers 15 In those days, Peter, rising up in the midst of the brothers, said (now the crowd of men altogether was about one hundred and twenty) 16 "Noble brothers, the Scripture must be fulfilled, which the Holy Spirit predicted by the mouth of David about Judas, who was the leader of those who apprehended Jesus 17 He had been numbered among us, and he was chosen by lot for this ministry 18 And this man certainly possessed an estate from the wages of iniquity, and so, having been hanged, he burst open in the middle and all his internal organs poured out 19 And this became known to all the inhabitants of Jerusalem, so that this field was called in their language, Akeldama, that is, ‘Field of Blood. 20 For it has been written in the book of Psalms: ‘Let their dwelling place be desolate and may there be no one who dwells within it,’ and ‘Let another take his episcopate. 21 Therefore, it is necessary that, out of these men who have been assembling with us throughout the entire time that the Lord Jesus went in and out among us 22 beginning from the baptism of John, until the day when he was taken up from us, one of these be made a witness with us of his Resurrection. 23 And they appointed two: Joseph, who was called Barsabbas, who was surnamed Justus, and Matthias 24 And praying, they said: "May you, O Lord, who knows the heart of everyone, reveal which one of these two you have chosen 25 to take a place in this ministry and apostleship, from which Judas prevaricated, so that he might go to his own place. 26 And they cast lots concerning them, and the lot fell upon Matthias. And he was numbered with the eleven Apostles