Musnad Ahmad

It is narrated from Hazrat Abu Hurairah (may Allah be pleased with him) that some people said, "O Messenger of Allah (peace and blessings be upon him), tell us of a deed that is equal to jihad." The Noble Prophet (peace and blessings be upon him) said, "You do not have the ability to do that" (he said this two or three times). The people said, "Please tell us, perhaps we can do it." The Noble Prophet (peace and blessings be upon him) said, "The example of the one who strives in the path of Allah is like that of a person who fasts during the day, stands in prayer at night, and humbles himself before the verses of Allah, and does not fall short in his fasting or prayer in any way, until the mujahid returns to his family."