Deuteronomy 16:8-10

New Catholic Bible

⁸ For six days you are to eat unleavened bread. Then, on the seventh day, you will hold a solemn assembly to the Lord, your God, and you are to do no heavy labor.

Feast of Weeks. ⁹ Count off seven weeks from the time that you put the sickle to the standing grain. You are to count off seven weeks, ¹⁰ and then you will celebrate the Feast of Weeks to the Lord, your God, making a freewill offering in proportion to how much the Lord, your God, has blessed you.