Raja' bin Haywah (may Allah have mercy on him) narrates from Sayyiduna Abu Umamah (may Allah be pleased with him): The Messenger of Allah (peace and blessings be upon him) set out on a military expedition, so I came to him (peace and blessings be upon him) and said: O Messenger of Allah, supplicate for martyrdom for me. He (peace and blessings be upon him) said: "O Allah, keep them safe and grant them spoils." We went on the expedition and returned safely. Then the Messenger of Allah (peace and blessings be upon him) set out on another expedition, and I said: O Messenger of Allah, supplicate for martyrdom for me. He (peace and blessings be upon him) said: "O Allah, keep them safe and grant them spoils." We went on the expedition, returned safely and also gained spoils. Then the Messenger of Allah (peace and blessings be upon him) set out on a third expedition, and I said: O Messenger of Allah, I have come to you twice asking you to supplicate for martyrdom for me, and you said: "O Allah, keep them safe and grant them spoils." We went on the expedition, returned safely and also gained spoils.
Then I said: O Messenger of Allah, tell me of a deed that I may learn from you. He (peace and blessings be upon him) said: "Hold fast to fasting, for there is no deed like it." So Abu Umamah (may Allah be pleased with him), his wife and his servant were always found fasting, and when they saw fire or smoke in their house, they would know that a guest had come to them.
Then after that I came to him (peace and blessings be upon him) and said: O Messenger of Allah, you commanded me with a deed by which I hope Allah will benefit me; now tell me of another deed by which Allah will benefit me. He (peace and blessings be upon him) said: "Know that you will not make a single prostration for Allah except that Allah will raise you a degree by it and wipe away a sin from you by it."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7432