Lu'lu' wal-Marjan

Sayyiduna Abdullah bin Amr (may Allah be pleased with him) narrated that news reached the Messenger of Allah (peace and blessings be upon him) about my fasting (that I fast continuously). He came to me, and I spread a mat filled with palm fibers for him, but the Messenger of Allah (peace and blessings be upon him) sat on the ground, and the cushion was placed between me and him. He said, "Is it not sufficient for you to fast three days in every month?" I said, "O Messenger of Allah, (increase it a little more for me)." He said, "Alright, fast five days." I said, "O Messenger of Allah, (increase it a little more)." He said, "Alright, six days." I said, "O Messenger of Allah, (increase it a little more, I have strength for more than this)." He said, "Alright, nine days." I said, "O Messenger of Allah, (increase it a little more)." He said, "Alright, eleven days." Finally, he said, "No method (in the Shari'ah) is permissible except the way of the fasts of Dawud (peace be upon him), that is, to fast one day and leave one day, in half the days of life."