You can listen to the sermon audio from DesiringGod.org. –The Ascent of Joy.
And Jesus said to them, „These are my words which I spoke to you, while I was still with you that, everything written about me in the law of Moses and the prophets and the psalms must be fulfilled.” Then he opened their minds to understand the scriptures and said to them, „Thus it is written, that the Christ should suffer and on the third day rise from the dead, and that repentance and forgiveness of sins should be preached in his name to all nations, beginning from Jerusalem. You are my witnesses of these things. And behold, I send the promise of my Father upon you; but stay in the city, until you are clothed with power from on high.”
And he led them out as far as Bethany, and lifting up his hands he blessed them. While he blessed them, he parted from them, and was carried up into heaven. And they worshipped him, and returned to Jerusalem with great joy, and were continually in the temple blessing God.
In the book of Acts, which Luke writes to continue his account of Jesus’ work in history (by his Spirit), he says (1:1–3):
In the first book, O Theophilus, I have dealt with all that Jesus began to do and to teach, until the day when he was taken up, after he had given commandment through the Holy Spirit to the apostles whom he had chosen. To them he presented himself alive after his passion by many proofs, appearing to them during forty days, and speaking of the kingdom of God.
Therefore, we learn that the ascension of Jesus back to the right hand of God the Father occurred forty days after the resurrection. Had it been Easter 1981 when Jesus was raised from the dead, the ascension would have occurred last Friday, day before yesterday. And had we been among the disciples, we would now find ourselves waiting in Jerusalem for the outpouring of God’s Spirit which came about ten days later on Pentecost. Therefore, today I want to focus our attention on the ascension of Jesus, and next Sunday on the meaning of Pentecost.