Abu Umama reported,

The Messenger of Allah ﷺ launched a military expedition, so I came to him and said, "Messenger of Allah, ask Allah to grant me martyrdom."The Messenger of Allah ﷺ said, "O Allah, keep them safe and grant them spoils."So we returned safely and with spoils.Then the Messenger of Allah ﷺ launched a second expedition, and I came to him and said, "Messenger of Allah, ask Allah to grant me martyrdom."He said, "O Allah, keep them safe and grant them spoils."So we returned safely and with spoils.Then he launched a third expedition, and I came to him and said, "Messenger of Allah, I have come to you twice before this time, asking you to pray to Allah to grant me martyrdom, and you prayed to Allah to keep us safe and grant us spoils, and we returned safely and with spoils. Messenger of Allah, ask Allah to grant me martyrdom."He said, "O Allah, keep them safe and grant them spoils."So we returned safely and with spoils.Then I came to him and said, "Messenger of Allah, command me to do a deed."He said, "Hold fast to fasting, for there is nothing like it."After that, Abu Umama, his wife, and his servant were never seen except fasting. Whenever smoke was seen rising from their house during the day, people would say, "A guest must have come to them, or some traveler has stopped by."Things continued this way for as long as Allah willed. Then I came to him and said, "Messenger of Allah, you commanded us to fast, and I hope Allah has blessed us in it. Messenger of Allah, command me to do another deed."He said, "Know that you will not prostrate to Allah a single prostration without Allah raising you a degree by it and erasing a sin from you because of it."

عن أبي أمامة قال

أنشأ رسول الله ﷺ غزوة، فأتيته فقلت: يا رسول الله، ادع الله لي بالشهادة، فقال رسول الله ﷺ: اللهم سلمهم وغنمهم. قال: فسلمنا وغنمنا. قال: ثم أنشأ رسول الله ﷺ غزوا ثانيا، فأتيته، فقلت: يا رسول الله، ادع الله لي بالشهادة، فقال: اللهم سلمهم وغنمهم. قال: فسلمنا وغنمنا. قال: ثم أنشأ غزوا ثالثا، فأتيته فقلت: يا رسول الله، إني أتيتك مرتين قبل مرتي هذه، فسألتك أن تدعو الله لي بالشهادة، فدعوت الله أن يسلمنا ويغنمنا، فسلمنا وغنمنا، يا رسول الله، فادع الله لي بالشهادة، فقال: اللهم سلمهم وغنمهم. قال: فسلمنا وغنمنا. ثم أتيته، فقلت: يا رسول الله، مرني بعمل، قال: عليك بالصوم فإنه لا مثل له. قال: فما رئي أبو أمامة ولا امرأته ولا خادمه إلا صياما، قال: فكان إذا رئي في دارهم دخان بالنهار، قيل: اعتراهم ضيف، نزل بهم نازل. قال: فلبثت بذلك ما شاء الله، ثم أتيته فقلت: يا رسول الله، أمرتنا بالصيام، فأرجو أن يكون قد بارك الله لنا فيه، يا رسول الله، فمرني بعمل آخر، قال: اعلم أنك لن تسجد لله سجدة إلا رفع الله لك بها درجة وحط عنك بها خطيئة.