Catena Fidei

1 Corinthians 15:5 (WEB)
and that he appeared to Cephas, then to the twelve.

Catechism · 4

§186Section Two · The CreedsRead at vatican.va
“From the beginning, the apostolic Church expressed and handed on her faith in brief formulae normative for all.” — Catechism footnote: Cf. Rom 10:9; I Cor 15:3-5, etc.

§552Paragraph 3 · The Mysteries of Christ's LifeRead at vatican.va
“Simon Peter holds the first place in the college of the Twelve;” — Catechism footnote: Cf Mk 3:16; 9:2; Lk 24:34; I Cor 15:5.

§641Paragraph 2 · On the Third Day He Rose from the DeadRead at vatican.va
“Peter had been called to strengthen the faith of his brothers,” — Catechism footnote: Cf I Cor 15:5; Lk 22:31-32.
§642Paragraph 2 · On the Third Day He Rose from the DeadRead at vatican.va
“Peter and the Twelve are the primary "witnesses to his Resurrection", but they are not the only ones - Paul speaks clearly of more than five hundred persons to whom Jesus appeared on a single occasion and also of James and of all the apostles.” — Catechism footnote: I Cor 15:4-8; cf. Acts 1:22.

Origen, Against Celsus II.62Book II
“And last of all He was seen of me also, as of one born out of due time.”” — editor's note: 1 Cor. xv. 3–8.
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Cyril of Jerusalem, Catechetical Lectures Lecture 15
“…of Cephas, then of the twelve; (for if thou believe not the one witness, thou hast twelve witnesses;) then He was seen of above five hundred brethren at once; (if they disbelieve the twelve, let them admit the five hundred;) after that He was seen of James, His own brother, and first Bishop of this diocese.” — editor's note: Ib. 5, 6.
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Eusebius of Caesarea, Church History I.11Book I
“…from the dead he appeared first to Cephas, then to the twelve, and after them to above five hundred brethren at once, of whom some had fallen asleep; but the majority were still living at the time he wrote.” — editor's note: See 1 Cor. xv. 5–7.
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John Cassian, Conferences XI–XVII XIV.8Conference XIV
“…that Christ died for our sins according to the Scriptures, and that He was buried, and that He rose again on the third day, and that he was seen of Cephas;” and: “God sent His Son, made of a woman, made under the law, to redeem them that were under the law;” or this: “Hear, O Israel, the Lord the God is one Lord.”” — editor's note: 1 Cor. xv. 3–5.
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Augustine of Hippo, Harmony of the Gospels III.26Book III
“And last of all He was seen of me also, as of one born out of due time.”” — editor's note: 1 Cor. xv. 3–8.
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