Acts of the Apostles 1:15-17.20a.20c-26.

During those days Peter stood up in the midst of the brothers (there was a group of about one hundred and twenty persons in the one place). He said, "My brothers, the scripture had to be fulfilled which the holy Spirit spoke beforehand through the mouth of David, concerning Judas, who was the guide for those who arrested Jesus.

  He was numbered among us and was allotted a share in this ministry. For it is written in the Book of Psalms: 'Let his encampment become desolate, and may no one dwell in it.' And: 'May another take his office.'

  For it is written in the Book of Psalms: 'Let his encampment become desolate, and may no one dwell in it.' And: 'May another take his office.'

  Therefore, it is necessary that one of the men who accompanied us the whole time the Lord Jesus came and went among us, beginning from the baptism of John until the day on which he was taken up from us, become with us a witness to his resurrection."

  So they proposed two, Joseph called Barsabbas, who was also known as Justus, and Matthias.
Then they prayed, "You, Lord, who know the hearts of all, show which one of these two you have chosen to take the place in this apostolic ministry from which Judas turned away to go to his own place."

  Then they gave lots to them, and the lot fell upon Matthias, and he was counted with the eleven apostles.

Psalms 103(102):1-2.11-12.19-20.

Bless the LORD, O my soul;
and all my being, bless his holy name.
Bless the LORD, O my soul,
and forget not all his benefits.

For as the heavens are high above the earth,
so surpassing is his kindness toward those who fear him.
As far as the east is from the west,
so far has he put our transgressions from us.

The LORD has established his throne in heaven,
and his kingdom rules over all.
Bless the LORD, all you his angels,
you mighty in strength, who do his bidding.

First Letter of John 4:11-16.

Beloved, if God so loved us, we also must love one another. No one has ever seen God. Yet, if we love one another, God remains in us, and his love is brought to perfection in us.

  This is how we know that we remain in him and he in us, that he has given us of his Spirit. Moreover, we have seen and testify that the Father sent his Son as savior of the world.

  Whoever acknowledges that Jesus is the Son of God, God remains in him and he in God. We have come to know and to believe in the love God has for us. God is love, and whoever remains in love remains in God and God in him.

Holy Gospel of Jesus Christ according to Saint John 17:11b-19.

And now I will no longer be in the world, but they are in the world, while I am coming to you. Holy Father, keep them in your name that you have given me, so that they may be one just as we are.

  When I was with them I protected them in your name that you gave me, and I guarded them, and none of them was lost except the son of destruction, in order that the scripture might be fulfilled.

  But now I am coming to you. I speak this in the world so that they may share my joy completely.

 
  I gave them your word, and the world hated them, because they do not belong to the world any more than I belong to the world.

  I do not ask that you take them out of the world but that you keep them from the evil one.They do not belong to the world any more than I belong to the world.

  Consecrate them in the truth. Your word is truth. As you sent me into the world, so I sent them into the world. And I consecrate myself for them, so that they also may be consecrated in truth.