Exodus 34:22-24

22You shall observe and celebrate the Feast of Weeks (Harvest, First Fruits, or Pentecost), the first fruits of the wheat harvest, and the Feast of Ingathering (Booths or Tabernacles) at the year’s end.

23Three times a year all your males shall appear before the Lord God, the God of Israel.

24For I will drive out and dispossess nations before you and enlarge your borders; nor shall any man covet (actively seek for himself) your land when you go up to appear before the Lord your God three times a year.