Chapter: The Position That Faith Is Affirmation in the Heart, Profession by the Tongue, and Action with the Limbs, and That No One Is a Believer Unless All Three Qualities Are Present in Him

Muhammad ibn al-Husayn said: Know—may Allah have mercy on us and you—that the Muslim scholars hold that faith is obligatory upon all creation and that it consists of affirmation in the heart, profession by the tongue, and action with the limbs.

Then know that knowledge and affirmation in the heart do not suffice unless accompanied by a spoken profession of faith. Nor do knowledge in the heart and a spoken profession suffice until accompanied by action with the limbs. When all three qualities are complete in a person, he is a believer. This is established by the Quran, the Sunnah, and the statements of the Muslim scholars.

As for the faith that is obligatorily required of the heart, Allah Most High says in Sūrat al-Māʾida: “O Messenger, do not be grieved by those who hasten into disbelief” [al-Māʾida: 41]. And Allah Most High says: “Whoever disbelieves in Allah after having believed—except one who is compelled while his heart remains secure