Sayyiduna Abdullah bin Amr bin Al-As (may Allah be pleased with him) narrates that the Messenger of Allah (peace be upon him) sent a message to call me. (When I presented myself) the Prophet (peace be upon him) said: "Has it not been reported to me that you spend the whole night in voluntary prayers and fast during the day?" Then the complete hadith was narrated. He says that the Noble Prophet (peace be upon him) said: "Observe the fast of Dawud (peace be upon him), for he was the most devoted worshipper among people. He would fast one day and leave fasting the next day." Then he said: "Indeed, you do not know; perhaps you may be granted a long life." He says that now I wish I had accepted the concession which the Messenger of Allah (peace be upon him) had given me.