6And on the fifteenth day of the same month is the Feast of Unleavened Bread to the LORD; for seven days you shall eat unleavened bread. 7On the first day you shall have a holy convocation; you shall not do any ordinary work.
31Since it was the day of Preparation, and so that the bodies would not remain on the cross on the Sabbath (for that Sabbath was a high day), the Jews asked Pilate that their legs might be broken and that they might be taken away.
Is he saying:
a) the upcoming day (which starts at sunset) is a Sabbath i.e. 7th day of week AND it falls on Nisan 15?
Or, if the upcoming day is Nisan 15 and NOT the 7th day of the week, is John saying:
b) Nisan 15 is a sabbath because Leviticus 23 says to rest
Based on reading a bunch of English translations, it seems (a) is correct.