First it’s necessary to define Sabbath. A Sabbath was a day in which no work was to be done. The seventh day of the week was always a Sabbath, so Saturday is always a Sabbath. There were other days also designated as Sabbaths, though, but Passover wasn’t one of them.
Nisan 14 (the first month) was Passover. On this day (which ran from evening to evening) the Lamb was slaughtered, roasted, and eaten entire – nothing was to be left for the next day.
Nisan 15 began the feast of Unleavened Bread. This was the day the Israelites set out from Egypt, and the point was that they went in haste and didn’t have time to leaven their dough so they ate unleavened cakes. This was a high Sabbath (a Sabbath feast day in addition to the usual Saturday Sabbath). The feast of Unleavened bread lasted seven days and the last day (the 21st) would also be a high Sabbath.
The we have an unspecified feast day, of First Fruits, which was to fall “on the morrow of the Sabbath;” that is, on Sunday. It was apparently (and still is) celebrated during the feast of Unleavened Bread.
So here is the chronology:
Nisan 14: Passover (or the evening before official Passover day as Jason suggested, which makes sense. I figured they must have done that but didn’t know it was sanctioned – and if they celebrated after Sunset, it would still be officially Passover as Jewish days are from sunset to sunset.)
Nisan 15: (Still the 14th according to Hebrew reckoning – until sunset) Jesus, who has all night been being tried, tortured, etc., is crucified and dies before sunset. At sunset begins the feast of Unleavened Bread – a high Sabbath but not necessarily a Saturday.
Nisan 16 or 17 (depending on where the days of the week fall that year): Feast of First Fruits in which the first of the harvest is offered to Yahweh. Before this offering is made, no produce from the new harvest is to be eaten.
So it would make sense that the day Jesus died they were hurrying to get His body to the tomb before sunset brought in the Sabbath. This Sabbath was the first day of Unleavened Bread and lasted until sunset the next day. So that’s either one day or two days depending on whether you count the day Jesus died as a full day (which was, I’m told, general practice – to count the part as a whole).
The next day was the usual seventh day Sabbath (or it was Sunday), so in the first case, no one could buy and bring spices that day until sunset. We’re told though, that the women went and bought spices. Would that be possible on the evening following two Sabbaths in a row? Maybe. It’s possible that after two days of no business the merchants would see this as a good time to open up shop – maybe someone else here knows.
So, on the first day of the week, whether evening or morning, the women came to the tomb and were told He was risen. Third day.
Personally, I think a Thursday crucifixion followed by back to back Sabbaths best answers the information we’re given, and I’m guessing that’s what this topic is all about – how to fit in those three days and nights in Sheol. For me, it would take a lot of convincing to persuade me away from Jesus’ resurrection being accomplished on the feast of the First Fruits. It’s just too perfect and too like Father to do that.
But there’s more . . . from First Fruits the Jews were to count off fifty days and (again on “the morrow of the Sabbath”) bring in two wave loafs (with leaven – symbolic, I’m told, of the gentiles) of fine flour as an offering. This is a kind of “second first fruits” offering because it comes from the first harvest. This feast the Jews call Pentecost, which was also (coincidentally?) the day of the birth of the church.
There are two more harvests to follow: the wheat and the grape harvest. A point which, I think, has largely been missed by the church. Also, Paul’s point that, if the firstfruits are holy, the lump (the bulk of the harvest) is holy also.