Basil Lourié has drawn my attention to a testimonium of Timothy Ailuros preserved in Armenian, most easily accessed (or at least most easily accessed by unlettered parish priests) through the translation of F. C. Conybeare, “The patristic testimonia of Timotheus Aelurus (Irenaeus, Athanasius, Dionysius)” JTS 15 (1913), 432-442, at 437-442. This collection of testimonia includes a citation of Melito of Sardis, attributed to Irenaeus, which is also found in Syriac (see elsewhere on the blog.) However, the reason for drawing attention to it here and now is the discussion of sabbath and Sunday drawn from the correspondence of Dionysius of Alexandria, which is related to the passion chronology. Dionysius is arguing that the day concludes at nightfall. Were it otherwise, and the following night to be counted as part of a day, then he suggests that the resurrection would have occurred not on the third day but on the second.
In the process he takes issue with those who reckon that the darkness which fell at the crucifixion is to be reckoned as a night, and so compute the three days as including three nights, beginning with this “nightfall” on the Friday. This is precisely the calculation employed in the Didascalia at 5.13.9-13a:
And they crucified him on the Friday. He suffered at the sixth hour on Friday. These hours in which our Lord suffered were reckoned as a day, 10and then there was darkness for three hours, and this was reckoned a night. And again, there were three hours, from the ninth hour until evening, – a day, and afterwards the night of the sabbath of the passion. Now in the Gospel of Matthew it is written thus: ‘On the evening of the sabbath as the first day of the week was dawning came Mary and the other Mary, Magdalene, to see the tomb. And there was a great earthquake, for an angel of the Lord came down and rolled the stone away.’ And so there was the day of the sabbath, and three hours of the night which were after the sabbath when our Lord was sleeping. And what he had said was fulfilled, that the son of man should spend three days and three nights in the heart of the earth, as it is written in the Gospel.
Not having otherwise met such a calculation, I am intrigued to find it here, and wonder whether it might have been more widespread than I had previously thought.
On another note, Dionysius (on the assumption that the attribution is correct) seems to support the evidence of Socrates HE 5.22 that worship at the close of sabbath continued in Egypt.