Deuteronomy 16:8-10 New Revised Standard Version (NRSV)
8 For six days you shall continue to eat unleavened bread, and on the seventh day there shall be a solemn assembly for the Lord your God, when you shall do no work.
The Festival of Weeks Reviewed
9 You shall count seven weeks; begin to count the seven weeks from the time the sickle is first put to the standing grain. 10 Then you shall keep the festival of weeks to the Lord your God, contributing a freewill offering in proportion to the blessing that you have received from the Lord your God.