Narrated `Abdullah bin `Amr: The news of my fasting was mentioned to the Prophet . So he entered upon me and I put for him a leather cushion stuffed with palm-fibres. The Prophet sat on the floor and the cushion was between me and him. He said to me, Isn't it sufficient for you (that you fast) three days a month? I said, O Allah's Apostle! (I can fast more than this). He said, You may fast) five days a month. I said, O Allah's Apostle! (I can fast more than this). He said, (You may fast) seven days. I said, O Allah's Apostle! He said, Nine. I said, O Allah's Apostle! He said, Eleven. I said, O Allah's Apostle! He said, No fasting is superior to the fasting of (the Prophet David) which was one half of a year, and he used, to fast on alternate days. (See Hadith No. 300, Vol 3)