Shevuos

Shevuos,* the Jewish Feast of Weeks, also called Pentecost, because it is celebrated on the fiftieth day after the second day of Passover, as we shall presently explain it, is also called the Feast of Harvest—“Yom Havicorim”—the day of the first ripe fruits, as on this day the first fruits were brought as offerings in the temple.

Tuesday evening and Wednesday morning, Jews observed the festival of Shevuos in celebration of the giving of the Ten Commandments to Moses, the children of Israel, and through them to all mankind.

Thus what’s especially wonderful at this time, this year, Shevuos comes out on Sabbath and they will both be celebrated together. […] Services will begin at 9:00 a.m. on Friday and Saturday, the two days of Shevuos and will be ushered in on Thursday night and Friday night at 8:00 p.m.