Deuteronomy 16
16 Ref Three times in the year let all your males come before the Lord your God in the place named by him; at the feast of unleavened bread, the feast of weeks, and the feast of tents: and they are not to come before the Lord with nothing in their hands;
17 Ref Every man is to give as he is able, in the measure of the blessing which the Lord your God has given you.