In the Acts of the Apostles, there is a short interval of days between the Ascension of Jesus and the coming of the Holy Spirit at Pentecost.
What happened during those days? What did the apostles do between the Ascension and Pentecost?
While we don't know all the details of what they did, the Acts of the Apostles does provide some clues and some specific actions that they did during those days.
Devoted themselves to prayer
Immediately following Jesus' ascension, the apostles and the Virgin Mary gathered together in the upper room to pray. This is the same location where Jesus celebrated the Last Supper.
All these devoted themselves with one accord to prayer.
This particular note is often why many Catholics pray a "novena" of prayer between the Ascension and Pentecost. There are nine days between Ascension Thursday and Pentecost Sunday, which is where the popular devotion of novenas has its origin.
Replaced Judas with Matthias
Besides prayer, they were also quite active during these days. The Acts of the Apostles explains,
"During those days ... they gave lots to them, and the lot fell upon Matthias, and he was counted with the eleven apostles" (Acts 1:15, 26).
The apostles needed to replace Judas and chose Matthias, a disciple of Jesus who was with them throughout Jesus' public ministry.
In a homily of St. John Chrysostom that is featured in the Church's Office of Readings, we learn there were very specific requirements that the replacement needed to meet before they were even considered.
So, he goes on, we must choose from those men who lived in our company. Notice how insistent he is that they should be eyewitnesses. Even though the Spirit would come to ratify the choice, Peter regards this prior qualification as most important. Those who lived in our company, he continued, all through the time when the Lord Jesus came and went among us. He refers to those who had dwelt with Jesus, not just those who had been his disciples. For of course from the very beginning many had followed him.
This requirement, along with being a witness of the Resurrection, qualified Matthias to replace Judas.
Gathered for the Jewish feast of Pentecost
The apostles and the Virgin Mary made the necessary preparations for the Jewish feast of Pentecost.
Pentecost is the Greek name for the festival known as the Feast of Weeks, or Shavuot in Hebrew.
It is, together with Pesach and Sukkot, one the three pilgrimage feasts of Israel, during which each adult male was required to be present in Jerusalem (cf. Ex 23:14-17).
This helps explain why all were present in Jerusalem, and also gives some insight into what they may have been doing during this time.
