Sunan An-Nasa'i

Abduallah bin amr bin Al-'As said:""The Messenger of Allah heard that I was fasting continually and praying all night."" Either he sent for him, or he happened to meet him and he said: ""Have I not been told that you fast and never break your fast, and you pray all night? Do not do that, for do that, for your eyes should have a share, your self should have a share, and your family should have a share. Fast and break your fast; pray and sleep. Fast one day out of every ten, and your will have the reward of the other nine."" He said: "" I am able to do more than that, O Messenger of Allah."" He said: ""Observe the fast of Dawud then."" "" I said: 'How did Dawud fast, O Prophet of Allah? He said: 'He used to fast one day, and not the next, and he never fled if he met(the enemy in battle).""' He said: ""How can I compare to him, O Prophet of Allah?