The festival of Shavu’ot superimposes the giving of the Spirit in Jerusalem over the giving of the Torah at Sinai. The two events are forever inseparably linked.
The ancient Jewish sages considered the biblical festival of Shavu’ot—also known as Pentecost—to be the anniversary of the day God spoke the Law at Mount Sinai.[1]
“Three times a year you shall celebrate,” the Bible says (Exodus 23:14-17). For as long as the Temple stood in Jerusalem, all the men of Israel were commanded to make pilgrimage there and worship God on the festivals of Pesach (Passover), Shavu’ot (Weeks) and Sukkot (Tabernacles):
Three times a year all your men must appear before the LORD your God at the place he will choose:[2] at the Feast of Unleavened Bread, the Feast of Weeks and the Feast of Tabernacles. (Deuteronomy 16:16)
This explains why there were so many Jews from all over the world in Jerusalem as recorded in Acts chapter 2. They had come to celebrate the festival of Shavu’ot.