Deuteronomy 16:7-9

New International Version - UK

⁷ Roast it and eat it at the place the Lord your God will choose. Then in the morning return to your tents. ⁸ For six days eat unleavened bread and on the seventh day hold an assembly to the Lord your God and do no work.

The Festival of Weeks

⁹ Count seven weeks from the time you begin to put the sickle to the standing corn.