Imam Abu Bakr (may Allah have mercy on him) says that in the hadith of Sayyiduna Talhah bin Ubaidullah (may Allah be pleased with him), in which a Bedouin asked the Prophet Muhammad (peace and blessings be upon him) about Islam, it is mentioned that the Prophet (peace and blessings be upon him) said: "And the fasting of Ramadan is obligatory." He asked, "Are there any other fasts obligatory upon me besides the fasts of Ramadan?" The Prophet (peace and blessings be upon him) said: "No, except that you observe voluntary fasts."

The horses of Banu Amir bin Sa’sa’ah, Hazrat Mutarrif narrates that Hazrat Uthman bin Abi al-As Thaqafi (may Allah be pleased with him) asked for milk to be brought for him to drink, so Hazrat Mutarrif said,“I am fasting.”He (Uthman) replied,“I heard the Prophet Muhammad (peace and blessings be upon him) say: ‘Fasting is a shield from the fire of Hell just like the shield of any one of you in battle.’ And I heard the Messenger of Allah (peace and blessings be upon him) say: ‘The best fasts are three days in every month.’”