Exodus 34:21-23

34:21 “On six days you may labor, but on the seventh day you must rest; even at the time of plowing and of harvest you are to rest.

34:22 “You must observe the Feast of Weeks – the firstfruits of the harvest of wheat – and the Feast of Ingathering at the end of the year. 34:23 At three times in the year all your men must appear before the Lord God, the God of Israel.