One of my favorite hadiths or prophetic anecdotes teaches: “Purity is half of faith, prayer is a light, charity is proof, and patience is illumination”. The Arabic word meaning ‘purity’ in this prophetic tradition is ‘Taharat’ which encompasses two spiritual dimensions: (1) taharat-e-batini, inner purity and (2) taharat-e-zahiri, outward purity. Through avoiding evil thoughts and engaging in continuous spiritual contemplation (dikr) Taharat-e-Batini or inner purity can be attained by a clean and pure thought cycle. It directly helps the heart and mind to be pure and sound, cleansing them from spiritual illnesses like anger, hatred, jealousy, selfishness etc. Nevertheless, Taharat-e-Zahiri or external purity is accomplished by properly preserving the physical cleanliness — for example, making wudu (ablution), taking a shower (ghusl), using fragrances or perfumes (itar) and keeping the house and clothes clean and tidy.
One of India’s earliest Sufis, Hazrat Data Ganj Baksh Hijweri states in his mulfuzat (Sufi discourses): “After iman (faith in God), the Sufi life style’s most imperative link is Taharat, which includes both kinds of cleanliness: body and mind purity. Just as meditation or devotion without Taharat-e-Zahiri can not be embraced, so can wisdom or ma’arifat not be achieved without Taharat-e-Batini. Often known as tazkiyah (soul purification), the latter is. The Sufism or tasawwuf practice is, in fact, nothing but tazkiyah. Tazkiyah empowers us to curb all the evil forces (quwwah-e-wahmiyya), violent thoughts (quwwa-e-ghazabiyya) and animalistic urges (quwwah-e-shahwania). So Prophets, their nearest companions (Sahaba) and Sufis used to profess the tazkiyah and practice it. Sometimes they would urge: “Purify yourself, you won’t have any sickness.” They have therefore pointed to different types of disease arising from moral and spiritual illnesses.