Letter 114: This is the explanation of the three periods of day and night of Our Lord’s entombment.
Isidore of Pelusium→Timothy Reader|c. 393 AD|Isidore of Pelusium|Human translated
grief deathimperial politics
Let the great Apostle himself, who labored more than all and followed the law precisely, teach you that knowledge of divine instruction under the law was childish, as though veiled in shadow and dimly perceived. "The law had a shadow of the good things to come," he declared, not the very image of the realities. The shadow pointed toward the substance, and the substance has now arrived in Christ.
This is the explanation of the three periods of day and night of Our Lord’s entombment. It is written “Just as Jonah was in the belly of the whale for three days and three nights; so the Son of Man will be in the heart of the earth for three days and three nights. He who promised fulfilling the prefiguration (type) of Jonah and who understands it accurately, since He was present with Jonah when he was thrown into the deep, and when he was vomited forth from the depth, fulfilled Jonah unfailingly, dwelling in the tomb as long as Jonah (did) in the whale; If you seek a second figure, this is it: At the sixth hour of Friday the Lord was crucified. From then until the ninth there was darkness; Take this from me to be night. Again from the ninth hour; this is again day. Then there is the Friday night, then the Sabbath. The night of the Sabbath is the morning of Sunday, according to the Evangelist who states “When it dawned on the first day of the week” If you wish to learn a third reason, (it is) as follows. On the Friday the Lord gave up His spirit; this is one day. He passed the whole of the Sabbath in the grave; then there is the night belonging to the Sabbath. When Sunday dawned, He rose from the tomb, and this is day. Since, as you know, from knowing a part the whole is known[16]. For in this way we are accustomed to perform the remembrance of those who die. At whatever hour of the day someone dies, the following day only is omitted, and on the next day from dawn we hold the third day of his (commemoration). You have, I think, the solution to what you were seeking. For if those who fight dishonestly ask for three complete days and nights, reply that, if the emperor was receiving the supplication and petition of those in the mines or in prison and promised to give them release after the third day, and in advance of the set date granted them their freedom, it was rather by his rapidity that he declared the truth (of his intention). The Master, rising more swiftly than He had promised, will appropriately be worshipped by all.
Let the great Apostle himself, who labored more than all and followed the law precisely, teach you that knowledge of divine instruction under the law was childish, as though veiled in shadow and dimly perceived. "The law had a shadow of the good things to come," he declared, not the very image of the realities. The shadow pointed toward the substance, and the substance has now arrived in Christ.
Human translation — Roger Pearse (additional translations)