of the remaining pillars of Islam, it was therefore appropriate to place before it the matters that prepare for it—foremost among them purification, for it is the key to the prayer, as the hadith states: “The key to the prayer is purification.” Ritual impurity (ḥadath) prevents one from performing the prayer; it is like a lock fastened upon the impure person, and when he performs ablution the lock is released.

Purification is thus the strongest of the prayer’s conditions, and a condition must necessarily precede that which it conditions.

Linguistically, ṭahārah means cleanliness and freedom from both tangible and intangible filth. In the legal sense, it is the removal of ritual impurity and the elimination of physical defilement.

Ritual impurity is lifted by using water, along with intention, over the entire body if the impurity is major, or over the four limbs if it is minor; alternatively, when water is unavailable or one is unable to use it, the substitute is earth (tayammum) applied in a specific manner. The procedure for purifying oneself from both types of impurity will, God willing, be explained later.

Our concern at present is to describe the kind of water that effects purification and the kind that does not.

Allah the Exalted says, “We sent down from the sky water that is purifying” (Q 25:48), and He says, “He sent down upon you water from the sky so that He might purify you with it” (Q 8:11).