Abu Mulaikh narrates: I presented myself before Sayyiduna Abdullah bin Amr (may Allah be pleased with him), and he narrated this hadith to us that the (supererogatory) fasting of mine was mentioned before the Prophet (peace and blessings be upon him). So the Prophet (peace and blessings be upon him) came to me, and I presented a pillow made of leather filled with leaves. The Prophet (peace and blessings be upon him) sat on the ground, and that pillow was between me and him. He asked: Is it not sufficient for you to fast three days in every month? I said: O Messenger of Allah (peace and blessings be upon him)! (Allow me more.) The Prophet (peace and blessings be upon him) said: Five. I said: O Messenger of Allah (peace and blessings be upon him)! (Allow me more.) The Prophet (peace and blessings be upon him) said: Seven. I said: O Messenger of Allah (peace and blessings be upon him)! (Allow me more.) The Prophet (peace and blessings be upon him) said: Nine. I said: O Messenger of Allah (peace and blessings be upon him)! (Allow me more.) The Prophet (peace and blessings be upon him) said: Eleven. I said: O Messenger of Allah (peace and blessings be upon him)! (Allow me more.) The Prophet (peace and blessings be upon him) said: No one can fast more than the way of fasting of Sayyiduna Dawud (peace be upon him), which is half of the time. One day fasting and one day not fasting.
Hadith Referenceصحیح ابن حبان / كتاب الصوم / 3640
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - «التعليق الرغيب» (2/ 88): ق.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرط مسلم