Sayyiduna Abdullah bin Amr (may Allah be pleased with him) narrated that the Messenger of Allah (peace and blessings be upon him) came to know that I observe fasts continuously and spend the whole night in worship. Now, either the Prophet (peace and blessings be upon him) sent someone to me or I myself met him. He (peace and blessings be upon him) asked,“Is it true what I have heard, that you fast continuously without missing a day and spend the whole night in prayer?”(He said:)“Observe the fast and also leave it (i.e., do not fast every day), worship and also sleep, for your eyes have a right over you, your soul has a right over you, and your wife has a right over you.”Sayyiduna Abdullah (may Allah be pleased with him) said,“I have the strength for more than this.”He (peace and blessings be upon him) said,“Then fast like Dawud (peace be upon him).”He asked,“And how was that?”He (peace and blessings be upon him) replied,“Dawud (peace be upon him) used to fast one day and leave fasting the next day. And when he faced the enemy, he would not turn his back.”Upon this, Sayyiduna Abdullah (may Allah be pleased with him) said,“O Messenger of Allah, how can it be possible for me to turn my back?”Hazrat Ata (the narrator of the hadith) said,“I do not remember how the fast of a lifetime (sawm ad-dahr) was mentioned in this hadith (but I do remember this much that) the Prophet (peace and blessings be upon him) said, ‘Whoever observes the fast of a lifetime, there is no fast for him,’ and he said this twice.”