Deuteronomy 16:8-10 New English Translation (NET Bible)
8 You must eat bread made without yeast for six days. The seventh day you are to hold an assembly for the Lord your God; you must not do any work on that day.
The Festival of Weeks
9 You must count seven weeks; you must begin to count them from the time you begin to harvest the standing grain. 10 Then you are to celebrate the Festival of Weeks before the Lord your God with the voluntary offering that you will bring, in proportion to how he has blessed you.