As far as I have learned, an annual feast day can fall on a Sabbath (the seventh day of the week). However, in the year Jesus was crucified that didn’t happen. That is, the annual feast day and the Sabbath were on two different days.
Because, if they fell on the same day, there would be a major contradiction in the gospels, as follows:
“And the sabbath passing, Mary Magdalene and Mary the mother of James
and Salome, bought spices, so that coming they might anoint Him.”
"And returning, they prepared spices and ointment. And indeed they
rested on the sabbath, according to the commandment.”
Mark says the ladies “bought” spices AFTER the Sabbath was over. This would take some time because they either had to go to the market to buy the spices or arrange them to be supplied. From the Bible, it is clear that the Sabbath ends at sunset. Did they go to market in the night itself or on the following day? Most probably, the latter could be the possible option. Also they need time to “prepare/process the spices and ointment”, (See Luke 23:56).
Whatever it is, they reached at the Tomb only on Sunday morning with the items ready with them.
But Luke says the ladies prepared the spices and ointment (which they had bought earlier) BEFORE the Sabbath.
But one thing we can be sure of: the Sabbath Luke talks about is the week day Sabbath (the seventh day) because he identifies it as the Sabbath “according to the commandment”.
Obviously these cannot be the same Sabbaths. The second Sabbath mentioned by Luke is, without any doubt, the seventh day Sabbath. Then what about the first Sabbath Mark talks about? This must be the first day of the Feast of Unleavened Bread, which falls, every year, right after the Passover day. The first day of the UB falls on Nissan 15, sunset to sunset. It is to be a rest day without work; so a shabbath.
Of necessity, there should be at least one day gap between these two Sabbaths. After the first annual Sabbath, the ladies went to or arranged someone to go to market, buy the required spices and other things and prepare them ready for anointing (pounding, grinding, drying in sunlight?).
It is this first Sabbath that followed the Passover day that John calls a “great” day (John 19:31). As far as my knowledge goes, the seventh day Sabbath is never called a great day in the Bible.
It is clear that Jesus was not crucified before the seventh day Sabbath. He was crucified before the UB, that is, exactly on the daytime of the Passover day.
That is why Paul declares: “For Christ, our Passover lamb, has been sacrificed” (1 Corinthians 5:7).
Yes, the Passover with a lamb “without blemish” in the Old Testament was “a shadow” of the “coming” great Sacrifice of Christ “without sin” in the New Testament!
So viewed in this way, Christ will stand vindicated when He said, “And even as "Jonah was in the belly of the huge fish three days and three nights," so shall the Son of Man be in the heart of the earth three days and three nights” (Matthew 12:40).
Jesus said, just as Jonah, He will be in the grave (heart of the earth) three days and three nights. (He didn’t mean the total time of His death but only the time when He will be buried!).
Did Jesus have any notion about the length of a day and night?
“Jesus answered, Are there not twelve hours in the day?” (John 11:9).
Yes, Jesus knew what He was saying when He said three days and three nights and He knew exactly how long these days would be!