A yearly fast before the feast of Saints Peter and Paul (July 12), called Petrivka, this year begins on June 20. It is not as strict as Lent, but according to the tradition of the Kyivan Church, meat and diary products are forbidden on weekdays.
Saint John Chrysostom said that “the apostles almost always kept the fast.” Through prayer and fasting they were preparing themselves to the descent of the Holy Spirit, to preaching of the Gospels. Therefore the church urges believers to imitate the apostles by praying and fasting and thus preparing for their feast.
The fasting of the holy apostles dates back to the first centuries of Christianity. Since the 4th century, there were the testimonies of Saint Athanase the Great and Saint Ambrose, and since the 5th century the testimonies of Pope Leo I and Theodoret of Cyrus. The oldest testimony about Petrivka was left by Saint Athanase the Great († 373).
According to the testimonies from the 4th century, in Alexandria, Jerusalem and Antioch the Apostles’ Fast was related not to the feast of Saints Peter and Paul but to Pentecost. In the first centuries, after Pentecost there was usually one week of rejoicing, that is, the Afterfeast of Pentecost, and then there was one week of fasting.
The Apostles’ Fast, as the Rev. Yulian Katriy writes in his book “Learn Your Rite,” was added into the practice of the church not through law but through tradition. Therefore no unanimity was reached either regarding its observance or its duration. Some were fasting for twelve days, others for six days, while still others for four days or one day.
The Apostles’ Fast in the Eastern Church lasts from the Sunday of All Saints till June 29 (July 12 according to the new style), the feast of Saints Peter and Paul. The duration of the fast can differ depending upon the date of Easter. The longest Petrivka can be for six weeks, and the shortest one for eight days.