Every man according as he
purposeth in his heart, [so let
him give]; not grudgingly, or
of necessity: for God loveth a
cheerful giver.  
- 2 Corinthians 9:7 KJV

Give, and it shall be given unto you; good measure, pressed down, and shaken together, and running over, shall men give unto your bosom.  For with the same measure that ye mete withal it shall be measured to you again. 
- Luke 6:38 KJV