Yearly
Ba'utha d-Ninwaye — the three days of Nineveh.
Three days of strict fasting in the weeks before Lent, kept in memory of the city that repented at Jonah's preaching — the city whose ruins are across the river from Mosul. The Book of Jonah is read through, and in many families nothing is eaten before evening. Every East Syriac church keeps it: Chaldean, Assyrian, Ancient, Syro-Malabar.
Go deeper — context →