Maymun bin Abi Shbyb ميمون بن أبي شبيب · The Book of Fasting

"For every good deed that the son of Adam does, he will have (the reward of) ten the like thereof, except for fasting. It is for Me and I shall reward for it.

"Raja bin Haiwah narrated that Abu Umamah said: 'I came to the Messenger of Allah and said: Tel l me of something that I may take (learn) from you. He said: "Take to fasting, for there is nothing like it."' '