Today's feast combines what were, until 1960, two separate feasts, namely of St Peter as bishop of Antioch, and St Peter as bishop of Rome.
The readings at Matins for today's feast are as follows:
Reading 1: Lesson from the first letter of St Peter the Apostle: Peter, an apostle of Jesus Christ, to the strangers dispersed through Pontus, Galatia, Cappadocia, Asia, and Bithynia, elect. According to the foreknowledge of God the Father, unto the sanctification of the Spirit, unto obedience and sprinkling of the blood of Jesus Christ: Grace unto you and peace be multiplied. Blessed be the God and Father of our Lord Jesus Christ, who according to his great mercy hath regenerated us unto a lively hope, by the resurrection of Jesus Christ from the dead, Unto an inheritance incorruptible, and undefiled, and that can not fade, reserved in heaven for you, Who, by the power of God, are kept by faith unto salvation, ready to be revealed in the last time.
Reading 2: Wherein you shall greatly rejoice, if now you must be for a little time made sorrowful in divers temptations: That the trial of your faith much more precious than gold which is tried by the fire) may be found unto praise and glory and honour at the appearing of Jesus Christ: Whom having not seen, you love: in whom also now, though you see him not, you believe: and believing shall rejoice with joy unspeakable and glorified; Receiving the end of your faith, even the salvation of your souls.
Reading 3: (Sermon of St Leo): For when the twelve Apostles, after receiving through the Holy Ghost the power of speaking with all tongues, had distributed the world into parts among themselves, and undertaken to instruct it in the Gospel, the most blessed Peter, chief of the Apostolic band, was appointed to the citadel of the Roman empire, that the light of Truth which was being displayed for the salvation of all the nations, might spread itself more effectively throughout the body of the world from the head itself. You had already taught the people, who from the number of the circumcised had believed: you had already founded the Church at Antioch, where first the dignity of the Christian name arose: you had already instructed Pontus, Galatia, Cappadocia, Asia, and Bithynia, in the laws of the Gospel-message: and, without doubt as to the success of the work, with full knowledge of the short span of your life carried the trophy of Christ's cross into the citadel of Rome, whither by the Divine fore-ordaining there accompanied you the honour of great power and the glory of much suffering.