Sayyiduna Abdullah bin Amr (may Allah be pleased with him) narrates: The Prophet Muhammad (peace and blessings be upon him) said to me, "I have come to know that you observe voluntary fasts every day and spend the whole night in voluntary prayers. If you continue like this, your eyes will sink in and your body will become weak. Whoever observes voluntary fasts every day has in fact not fasted. Fasting three days every month is equivalent to fasting the whole month. Sayyiduna Dawud (peace be upon him) used to fast one day and not fast the next day, and when he faced the enemy, he would not flee."