It is narrated from Sayyiduna Ibn Amr, may Allah be pleased with him, that the Noble Prophet, peace and blessings be upon him, said to me: "I have come to know that you fast all day and stand in prayer all night. Do not do so, for your body has a right over you, your eyes have a right over you, and your wife has a right over you. Fast only three days in every month; this will be equal to fasting all the time." I said, "I have strength for more than this." The Noble Prophet, peace and blessings be upon him, said: "Then adopt the way of Sayyiduna Dawud, peace be upon him: fast one day and leave one day." Later, Sayyiduna Ibn Amr, may Allah be pleased with him, said: "I used to do so. I wish I had accepted the concession of the Noble Prophet, peace and blessings be upon him."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 6862