B522 8 Steps to Happiness [Awakening the Inner Self in Pursuit of Personal Change]

By way of these various means, the Qur’ān calls the people to believe in the Sunnah and act upon it, and that it, along with the Qur’ān, is [one of] the true foundations of this religion. Since belief in the Messenger ﷺ is a foundation from the foundations of īmān, then belief in his Sunnah is a necessary component of īmān in him, because he is Ṣāḥib as-Sunnah (the Possessor of the Sunnah), and because īmān, as Imām Ibn al-Qayyim has defined it, is: