Fast of Nineveh
In the Oriental Orthodox Churches, the Assyrian Church of the East, the Ancient Church of the East, and in some certain Eastern Catholic Churches of the West Syriac Rite, the East Syriac Rite, the Alexandrian Rites (both Coptic and Ge'ez), and the Armenian Rite, the Fast of Nineveh (Classical Syriac: ܒܥܘܬܐ ܕܢܝܢܘܝ̈ܐ Bā'ūṯā ḏ-Ninwāyē, literally "Petition of the Ninevites"; Armenian: Արաջավորաց Բահկ; Arajavorats Bahk; literally "Fast of the Catechumens"), is a three-day fast (or a five-day fast in the Armenian Church) starting the third Monday before Clean Monday from Sunday evening after sun set to Wednesday noon (or, until Friday, in the Armenian Church), during which participants usually abstain from all dairy foods and meat products. However, some faithful, traditionally observe the fast more rigorously and abstain from food and drink altogether from Sunday midnight to Wednesday after the Divine Liturgy, which is celebrated before the afternoon. However, the Armenian Apostolic Church and the Armenian Catholic Church both have and observe a very distinct version of the fast, which they call the Arajavorats Bahk (the Fast of the Catechumens), which instead lasts for 5 consecutive days (from Monday to Friday) in mid-January (in contrast to the three day fast observed in all other Eastern churches who observe the fast), and which ends just before the Armenian Feast of St. Sarkis. In addition, the very distinctive Armenian version of the fast is also generally more rigorous as it generally involves complete abstinence from the consumption of all types of animal products during their five-day fast.
The three day fast of Nineveh commemorates the three days that Prophet Jonah spent inside the belly of the Great Fish and the subsequent repentance with fasting from food and water performed by the Ninevites at the warning message of the prophet Jonah (cf. Jonah 3).