Deuteronomy 16:10 in the King James Version
And thou shalt keep the feast of weeks unto the LORD thy God with a tribute of a freewill offering of thine hand, which thou shalt give unto the Lord thy God, according as the LORD thy God hath blessed thee:
Context
9 You shall count for yourselves seven weeks. From the time you begin to put the sickle to the standing grain you shall begin to count seven weeks.
10 You shall keep the feast of weeks to the LORD your God with a tribute of a free will offering of your hand, which you shall give according to how the LORD your God blesses you.
11 You shall rejoice before the LORD your God: you, your son, your daughter, your male servant, your female servant, the Levite who is within your gates, the foreigner, the fatherless, and the widow who are among you, in the place which the LORD your God shall choose to cause his name to dwell there.