Pentecost

As part of the law of Moses, the Feast of Pentecost or Firstfruits was held fifty days after the Feast of the Passover (Lev. 23:16). Pentecost was to celebrate the harvest, and in the Old Testament it is called the Feast of Harvest or the Feast of Weeks. It is this feast that was being celebrated when the Apostles in Jerusalem were filled with the Holy Ghost and spoke in tongues (Acts 2; D&C 109:36–37).