Veneration as a Forefather of Christ
Isaac is commemorated in the Orthodox calendar among the holy forefathers, the ancestors of Christ according to the flesh. He is honored individually on his feast and is also remembered, together with Abraham and Jacob and the other righteous ancestors, on the Sunday of the Holy Forefathers, which falls in the second half of December shortly before the Nativity.
These commemorations recall the covenant promise given to Abraham, 'In thy seed shall all the nations of the earth be blessed,' and present the patriarchs as part of the lineage and preparation leading to the Incarnation of Christ.