The Promise of the Holy Spirit 1
In my first book 
I told you, Theophilus, about everything Jesus began to do and teach
until the day he was taken up to heaven after giving his chosen apostles further instructions through the Holy Spirit.
During the forty days after his crucifixion, 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.
Once when he was eating with them, he commanded them, "Do not leave Jerusalem until the Father sends you the gift he promised, as I told you before.
John baptized with 
water, but in just a few days you will be baptized with the Holy Spirit."
The Ascension of Jesus 6
So when the apostles were with Jesus, they kept asking him, "Lord, has the time come for you to free Israel and restore our kingdom?"
He replied, "The Father alone has the authority to set those dates and times, and they are not for you to know.
"But you will receive power when the Holy Spirit comes upon you. And you will be my witnesses, telling people about me everywhere - in Jerusalem, throughout Judea, in Samaria, and to the ends of the earth."
After saying this, he was taken up into a cloud while they were watching, and they could no longer see him.
As they strained to see him rising into heaven, two white-robed men suddenly stood among them.
"Men of Galilee," they said, "why are you standing here staring into heaven? Jesus has been taken from you into heaven, but someday he will return from heaven in the same way you saw him go!"
Matthias Replaces Judas 12
Then the apostles returned to Jerusalem from the Mount of Olives, a distance of half a mile. 
When they arrived, they went to the upstairs room of the house where they were staying.
Here are the names of those who were present: Peter, John, James, Andrew, Philip, Thomas, Bartholomew, Matthew, James (son of Alphaeus), Simon (the Zealot), and Judas (son of James).
They all met together and were constantly united in prayer, along with Mary the mother of Jesus, several other women, and the brothers of Jesus.
During this time, when about 120 believers 
were together in one place, Peter stood up and addressed them.
"Brothers," he said, "the Scriptures had to be fulfilled concerning Judas, who guided those who arrested Jesus. This was predicted long ago by the Holy Spirit, speaking through King David.
Judas was one of us and shared in the ministry with us."
(Judas had bought a field with the money he received for his treachery. Falling headfirst there, his body split open, spilling out all his intestines.
The news of his death spread to all the people of Jerusalem, and they gave the place the Aramaic name Akeldama,
which means "Field of Blood.")
Peter continued, "This was written in the book of Psalms, where it says, `Let his home become desolate, with no one living in it.' It also says, `Let someone else take his position.' 
"So now we must choose a replacement for Judas from among the men who were with us the entire time we were traveling with the Lord Jesus—
from the time he was baptized by John until the day he was taken from us. Whoever is chosen will join us as a witness of Jesus' resurrection."
So they nominated two men: Joseph called Barsabbas (also known as Justus) and Matthias.
Then they all prayed, "O Lord, you know every heart. Show us which of these men you have chosen
as an apostle to replace Judas in this ministry, for he has deserted us and gone where he belongs."
Then they cast lots, and Matthias was selected to become an apostle with the other eleven.