The Feast of Weeks, seven weeks after Passover, is celebrated for two days. In Biblical days the Hebrews would count seven weeks from Passover to Shavuot by bringing an omer or measure of barley to the Temple for forty-nine days, starting with the second evening on Passover, to give thanks to God for their produce during the barley season. In the absence of a written calendar, this was their way of determining the exact date of the Feast of Weeks. Even after the calendar was fixed and the sixth day of Sivan was made the date of the holiday, the name Feast of Weeks was retained. In traditional synagogues it is still customary to count the forty-nine days from the second evening of Passover to Shavuot.

In time, after the second Temple was destroyed, the Jews had to rely on their Torah to unite them rather than on their land, so they recalled the Ten Commandments that were given to Israel at Mount Sinai. The religious meaning of the holiday thus became more important than the agricultural meaning. Pesah, the "freedom from" festival, was a prelude to Shavuot- "freedom for" receiving God's eternal law. The giving of the Torah marked the end of Israel's childhood and its entry into national maturity. At the moment that it accepted the laws of justice, truth, and loving-kindness, Israel secured for itself a permanent existence.

On Shavuot, Jews rededicate themselves to the Torah by reading the passage containing the Ten Commandments. It is also customary to read the Book of Ruth on the festival of Shavuot, since it describes the grain harvest and the treatment of the poor during the harvest season. Ruth also embraces the Jewish faith by accepting the Torah.