On the feast of the Ascension, Fr. Matthew Howell explains why this is the feast of deification. He then goes on to point out three distinct references to the Ascension within the Divine Liturgy.
Acts of the Apostles 1:1-12
In the first book, O Theophilos, I have dealt with all that Jesus began to do and 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. And while staying with them he charged them not to depart from Jerusalem, but to wait for the promise of the Father, which, he said, “you heard from me, for John baptized with water, but before many days you shall be baptized with the Holy Spirit.” So when they had come together, they asked him, “Lord, will you at this time restore the kingdom of Israel?” He said to them, “it is not for you to know times or seasons which the Father has fixed by his own authority. But you shall receive power when the Holy Spirit has come upon you; and you shall be my witnesses in Jerusalem and in all Judea and Samaria and to the end of the earth.” And when he had said this, as they were looking on, he was lifted up, and a cloud took him out of their sight. And while they were gazing into heaven as he went, behold, two men stood by them in white robes, and said, “Men of Galilee, why do you stand looking into heaven? This Jesus, who was taken up from you into heaven, will come in the same way as you saw him go into heaven.” Then they returned from the mount called Olivet, which is near Jerusalem, a sabbath day’s journey away.
At that time, Jesus, having risen from the dead, stood in the midst of his disciples and said to them, “Peace to you.” But they were startled and frightened, and supposed that they saw a spirit. And he said to them, “Why are you troubled, and why do questionings rise in your hearts? See my hands and feet, that it is I myself; handle me, and see; for a spirit has not flesh and bones as you see that I have.” And when he said this, he showed them his hands and his feet. And while they still disbelieved for joy, and wondered, he said to them, “Have you anything here to eat?” They gave him a piece of broiled fish, and he took it and ate before them. Then he 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 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. Then 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 worshiped him, and they returned to Jerusalem with great joy, and were continually in the temple blessing God.