Deuteronomy 16:17
Every man shall give as he is able, according to the blessing of the LORD your God which He has given you.

2 Corinthians 9:6-8
Now this I say, he who sows sparingly will also reap sparingly, and he who sows bountifully will also reap bountifully. Each one must do just as he has purposed in his heart, not grudgingly or under compulsion, for God loves a cheerful giver. And God is able to make all grace abound to you, so that always having all sufficiency in everything, you may have an abundance for every good deed.