In talking about Pessaḥ, the Torah says that Shavuot begins seven complete weeks from “the day after Shabbat”. [Leviticus 23:15-16]
Which Shabbat? Unspecified. The Sadducees said it’s the Shabbat within the week of Pessaḥ. The Pharisees said it’s the first day of Pessaḥ, interpreted as a Shabbat (a day of rest, which it is also). They prevailed. [Menaḥot 65b]
Are there other instances in the Sources where a holiday is referred to as “Shabbat”? Why is it done?
