The Fast of the Apostles, though inspired from and attributed to the Holy Apostles, is however a dominical fast dedicated to the Holy Spirit. St. John of Mardin writes in his canon of Dayro d’Mor Hananyo; “The fast of the forty days (of the Nativity) is for the Father, the Great Fast of the Son is forty days except for the week of the saving Passion, and the third dominical fast which is for the Holy Spirit, is for fifty days from the Sunday after the Feast of the Pentecost.” Furthermore, Mor John of Dara states in his Commentary on Holy Qurobo that the Apostles themselves fasted until the fiftieth day after Pentecost.
Bar Ebroyo records in his Kthobo d-Hudoye (The Book of Guides, also known as Nomocanon) various traditions concerning the observance of this Fast. He mentions that some commenced the Fast the Monday following the feast of Pentecost while some others began on the second Monday following Pentecost. Nevertheless both concluded on June 29th with the feast of St. Peter and St. Paul. In the 19th century the duration of the Fast was shortened to thirteen days from June 16th to June 29th. Finally in the Council of Homs 1946, the period of the Fast was further reduced to three days i.e. June 26th – 29th.
The more distant the Fast got from the feast of Pentecost the more divorced it became from its theological import. Rather than glorifying “the Holy Spirit who perfects the Apostles” (Sedro of the Third Service of Pentecost) we appear to glorify the Apostles themselves. Although the Apostles walked with Christ and were taught by Christ Himself, they neither understood Christ nor His teachings until the reception of the Holy Spirit because faith is a gift of the Spirit (1 John 2:27). St. Basil the Great remarks; “Faith is superior to rational methodologies when it comes to drawing the soul to assent. It is not the logical necessity of deductive proofs that engenders faith, but the activity of the Spirit.” (Homily on Psalm 115).
It is the Spirit who enlightens our faculties, mediates our memory, and reminds us the teachings of Christ. As Christ Himself said; “The Holy Spirit, whom the Father will send in my name, will teach you everything and remind you of all that I have said to you.” (St. John 14:26). Therefore as we observe this Fast may we bear in mind the original purport of this Fast.
“You, who descended in the likeness of fiery tongues upon the Holy Apostles and made them perfect by divine gifts; You who were brilliantly revealed and made known to be consubstantial with the Father and the Son, make us also worthy of receiving the richness of your divine gifts.” (Litany of Pentecost)
~ Dayroyo Fr. Basil
Urho, The Way 