Sahih Bukhari
Beginning of Creation
Volume: 004 / Book Number: 054 / Hadith Number: 479
Narrated Sahl bin Sad:
The Prophet said, "Paradise has eight gates, and one of them is called Ar-Raiyan through which none will enter but those who observe fasting." The Prophet also said, "If a person spends two different kinds of something (for Allah's Cause), he will be called from the gates of Paradise."