Najasah (Ritual Impurity)

Najasah (Arabic: نجاسة) refers to the substances that are considered ritually impure in Islamic law. The presence of najasah on the body, clothing, or prayer area invalidates the prayer, and it must be removed (tathhir) with water or other purifying agents.

In Shia fiqh, there are ten categories of najis (impure) substances: (1) Urine, (2) Feces, (3) Semen, (4) Blood, (5) Dead body (maytah) without Islamic slaughter, (6) Dog, (7) Swine, (8) Alcoholic intoxicating drinks (khamr), (9) Non-Muslim disbeliever (kafir) according to some scholars, and (10) Sweat of an animal that eats najasah. These categories are based on narrations from Ahl al-Bayt and are described in detail in Al-Kafi and other hadith collections.

Imam al-Sadiq (peace be upon him) was asked about a man who prays with najasah on his clothing, and he answered: "If he knew about it and still prayed, he must repeat the prayer. If he did not know, his prayer is valid" (Wasail al-Shia by al-Hurr al-Amili, vol. 3). This narration illustrates the important principle that ignorance of najasah does not invalidate the prayer.

The primary means of removing najasah is water — either kurr water (a large quantity, at least 384 liters), running water, or a small amount of water (qalil) with a specific method. Additionally, there are other purifying agents (mutahhirat): earth purifies the soles of shoes, the sun purifies the ground and buildings, and Islam (conversion) purifies a person's body. Knowledge of najasah rules is essential for correct prayer practice.