Deuteronomy 16:10

And you shall celebrate the Feast of Weeks to the Lord your God with a freewill offering that you give in proportion to how the Lord your God has blessed you,

Note That is, Shavuot; see footnotes for verse 16.

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:

Note a tribute: or, sufficiency

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.

And thou shalt keep the feast of weeks unto Jehovah thy God with a tribute of a freewill-offering of thy hand, which thou shalt give, according as Jehovah thy God blesseth thee: