The Prophet (sallAllahu 'alyhi wasallam) said, “Every day two angels come down from Heaven and one of them says, ‘O Allah! Compensate every person who spends in Your cause’, and the other (angel) says, ‘O Allah! Destroy every miser.’” (Bukhari, Vol. 2, Hadith 522)

 
“The example of those who spend their wealth in the way of Allah is like a seed [of grain] which grows seven spikes; in each spike is a hundred grains. And Allah multiplies [His reward] for whom He wills. And Allah is all-Encompassing and Knowing.” (Al Qur’an, 2:261)