Aisha, the wife of the Prophet of Islam, says of him: “On every occasion, the Prophet of Islam remembered God.” (Sahih Muslim, Hadith No. 373). This tradition shows the prophetic way of purification, that is to say that the Prophet purified himself on all occasions. This shows that tazkiya is not the name of any short training course, but is rather a continuous process. When a believer discovers the truth, due to the awakening of his conscience, every event or experience in his life becomes a point of reference for his purification. This enables him to receive spiritual nourishment on a daily basis. In this way, this process of tazkiya continues till his last breath. Just as physical energy is generated by constant nourishment, so also is tazkiya achieved by constant effort. There is the general impression, however, that a brief training course is all that it takes to attain a state of tazkiya. That is, it is just like receiving religious education in a seminary within the limited frame of a short-term prescribed course of study. But the truth is that this is an underestimation of tazkiya.

Tazkiya, a cumulative process, and not the result of any fixed practice, requires an awakened mind. It is attained through an unflagging intellectual process and not by engaging in any temporary course of study.

Source: Discovering God