2 Corinthians 9:6 – 7
New International Version (NIV)
6 Remember this: Whoever sows sparingly will also reap sparingly, and whoever sows generously will also reap generously. 7 Each of you should give what you have decided in your heart to give, not reluctantly or under compulsion, for God loves a cheerful giver.
From BibleGateway.com: http://www.biblegateway.com/passage/?search=2+corinthians+9.6-7&version=NIV