It is narrated from Sayyiduna Ibn Amr (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said to me: "O Abdullah bin Amr! Always keep fasts, and the way to do this is to fast three days every month." Then the Noble Prophet (peace and blessings be upon him) recited this verse: "Whoever brings a good deed shall have ten times as much." I said, "I have the strength to do more than this." The Noble Prophet (peace and blessings be upon him) said: "Then fast like Sayyiduna Dawud (peace be upon him); he would fast one day and leave off the next day."