Deuteronomy 16:16-17

16Three times in the year shall all thy males appear before Jehovah thy 1God in the place which he will choose, at the feast of unleavened bread, and at the feast of weeks, and at the feast of tabernacles; and they shall not appear before Jehovah empty:

17each [shall give] according to that which is in his power to give, according to the blessing of Jehovah thy 2God which he hath given thee.