First Reading: Acts of the Apostles 1:15-17,20a,20c-26
15 In those days Peter rising up in the midst of the brethren, said: (now the number of persons together was about an hundred and twenty:)
16 Men, brethren, the scripture must needs be fulfilled, which the Holy Ghost spoke before by the mouth of David concerning Judas, who was the leader of them that apprehended Jesus:
17 Who was numbered with us, and had obtained part of this ministry.
20 For it is written in the book of Psalms: Let their habitation become desolate, and let there be none to dwell therein.And his bishopric let another take.
21 Wherefore of these men who have companied with us all the time that the Lord Jesus came in and went out among us,
22 Beginning from the baptism of John, until the day wherein he was taken up from us, one of these must be made a witness with us of his resurrection.
23 And they appointed two, Joseph, called Barsabas, who was surnamed Justus, and Matthias.
24 And praying, they said: Thou, Lord, who knowest the hearts of all men, show whether of these two thou hast chosen,
25 To take the place of this ministry and apostleship, from which Judas hath by transgression fallen, that he might go to his own place.
26 And they gave them lots, and the lot fell upon Matthias, and he was numbered with the eleven apostles.
Psalm: Psalms 103:1-2,11-12,19-20
1 For David himself. Bless the Lord, O my soul: and let all that is within me bless his holy name.
2 Bless the Lord, O my soul, and never forget all he hath done for thee.
11 For according to the height of the heaven above the earth: he hath strengthened his mercy towards them that fear him.
12 As far as the east is from the west, so far hath he removed our iniquities from us.
19 The Lord hath prepared his throne in heaven: and his kingdom shall rule over all.
20 Bless the Lord, all ye his angels: you that are mighty in strength, and execute his word, hearkening to the voice of his orders.
Second Reading: 1 John 4:11-16
11 My dearest, if God hath so loved us; we also ought to love one another.
12 No man hath seen God at any time. If we love one another, God abideth in us, and his charity is perfected in us.
13 In this we know that we abide in him, and he in us: because he hath given us of his spirit.
14 And we have seen, and do testify, that the Father hath sent his Son to be the Saviour of the world.
15 Whosoever shall confess that Jesus is the Son of God, God abideth in him, and he in God.
16 And we have known, and have believed the charity, which God hath to us. God is charity: and he that abideth in charity, abideth in God, and God in him.
Gospel: John 17:11b-19
11Holy Father, keep them in thy name whom thou has given me; that they may be one, as we also are.
12 While I was with them, I kept them in thy name. Those whom thou gavest me have I kept; and none of them is lost, but the son of perdition, that the scripture may be fulfilled.
13 And now I come to thee; and these things I speak in the world, that they may have my joy filled in themselves.
14 I have given them thy word, and the world hath hated them, because they are not of the world; as I also am not of the world.
15 I pray not that thou shouldst take them out of the world, but that thou shouldst keep them from evil.
16 They are not of the world, as I also am not of the world.
17 Sanctify them in truth. Thy word is truth.
18 As thou hast sent me into the world, I also have sent them into the world.
19 And for them do I sanctify myself, that they also may be sanctified in truth.