سنن النسائي

It was narrated from 'Abdullah bin 'Amr bin Al-As that it was mentioned to the Messenger of Allah (ﷺ) that he had said: "I will certainly stand all night (in prayer) and fast every day for as long as I live." The Messenger of Allah (ﷺ) said: "Are you the one who said that?" I said: 'I said it, O Messenger of Allah.' The Messenger of Allah (ﷺ) said: 'You cannot do that. Fast and break your fast, sleep and stand (in prayer), and fast three days of each month. For a good deed is equal to ten like it, and that is like fasting for a lifetime.' I said: 'But I am able to do bette than that.' He said: 'Fast for one day and break your fast for two days.' I said: 'I am able to do better than that, O Messenger of Allah.' He said: 'Then fast for one day and break your fast for two days.' I said: 'I am able to do better than that, O Messenger of Allah said : 'There is noting better than that."' 'Abdullah said: "If I had accepted the three days that the Messenger of Allah (ﷺ) said, that would be dearer to me than my family and my wealth." 'Ata said: "someone who heard him told me that Ibn 'Umar (said) that the Prophet (ﷺ) said: 'Whoever fasts every day of his life, then he has not fasted."