The obligations are mentioned in the Quran. Mulla Ali begins by listing the obliagation (fard) aspects of wudu:1. Wash your whole face from the hairline above your forehead to the chin and from ear to ear. This does not include the neck or ears. The mouth and nose are not considered fard in the Hanafi school, but are considered fard in the Shafi school. 2. Wash both your hands up to and including the elbows. 3. Wipe over the head. 4. Wash both feet up to and including the ankles. Washing between the toes is considered fard by some and Sunnah by the others.