Tonight at sundown, the Jewish community begins celebration of Shavuot or Weeks. Christians know this holiday from the New Testament as Pentecost. The festival is based on Leviticus 23:15-16 and was originally celebrated as an agricultural holiday, the first fruits of the grain harvest. Its annual celebration was on the 50th day following Passover. At a very early, stage the focus of the festival shifted to the celebration of God's giving of the Law (Torah) to Moses. Evidence is available in this shift as early as the second century of the common era. This is still the focus of the Jewish celebration of Shavuot.
Of course, Christians also continue to remember the importance of this festival, but for another reason. Often referring to it as the "birthday of the church," Christian tradition, based on Acts 2, remembers the festival as the time when the Holy Spirit was poured out on believers in Jesus as Lord and Christ (Messiah). Pentecost will be celebrated in most churches this coming Sunday.
The picture file is from Wikimedia Commons - Moses with the Tablets, 1659, by Rembrandt.