In this episode, Zohair Rahman of Yaqeen Institute joins us to discuss tazkiyah (self-purification.) We begin by exploring how the concept of tazkiyah is presented in the Qur'an and the Sunnah. We define the objective of tazkiyah, noting the difference between its ultimate purpose and the effects that it may produce for those who pursue it. Our discussion then ventures through a brief history of tazkiyah as a field of knowledge and practice, focusing on classical critiques of tendencies that emerged among its devotees. We go on to look at tazkiyah in terms of personal observances: how can we draw a line between what is legitimate and what might be bid'ah? Finally, we discuss the nature of tazkiyah as a discipline and the superiority of a shari'ah-bound tazkiyah to all other forms of spirituality and personal development.