Pentecost or Shavuot
The Feast of Weeks or Shavuot is celebrated seven weeks and one day (50 days) after The Feast of First Fruits to rejoice in the late spring wheat harvest. It is also called Pentecost, the Greek word for fiftieth.
Jewish tradition also calls this day The Time of the Giving of Our Torah when the Lord revealed Himself to His people at Mount Sinai; Mount Sinai quaked violently as He came in glory with thunder, fire, thick clouds and smoke to write His law on tablets of stone. (Exodus 19)