The Quran

Preface

يا أَيُّهَا الَّذينَ آمَنوا إِذا قُمتُم إِلَى الصَّلاةِ فَاغسِلوا وُجوهَكُم وَأَيدِيَكُم إِلَى المَرافِقِ وَامسَحوا بِرُءوسِكُم وَأَرجُلَكُم إِلَى الكَعبَينِ ۚ وَإِن كُنتُم جُنُبًا فَاطَّهَّروا ۚ وَإِن كُنتُم مَرضىٰ أَو عَلىٰ سَفَرٍ أَو جاءَ أَحَدٌ مِنكُم مِنَ الغائِطِ أَو لامَستُمُ النِّساءَ فَلَم تَجِدوا ماءً فَتَيَمَّموا صَعيدًا طَيِّبًا فَامسَحوا بِوُجوهِكُم وَأَيديكُم مِنهُ ۚ ما يُريدُ اللَّهُ لِيَجعَلَ عَلَيكُم مِن حَرَجٍ وَلٰكِن يُريدُ لِيُطَهِّرَكُم وَلِيُتِمَّ نِعمَتَهُ عَلَيكُم لَعَلَّكُم تَشكُرونَ

Yusuf Ali

O ye who believe! when¹ ye prepare for prayer, wash your faces, and your hands (and arms) to the elbows; Rub your heads (with water); and (wash) your feet to the ankles. If ye are in a state of ceremonial impurity,² bathe your whole body. But if ye are ill, or on a journey, or one of you cometh from offices of nature, or ye have been in contact with women, and ye find no water, then take for yourselves clean sand or earth,³ and rub therewith your faces and hands, God doth not wish to place you in a difficulty, but to make you clean, and to complete his favour to you, that ye may be grateful.

These are the essentials of Wudu', or ablutions preparatory to prayers, viz. (1) to bathe the whole face in water, and (2) both hands and arms to the elbows, with (3) a little rubbing of the head with water (as the head is usually protected and comparatively clean), and (4) the bathing of the feet to the ankles. In addition, following the practice of the Prophet, it is usual first to wash the mouth, the throat, and the nose, before proceeding with the face, etc.
Cf. 4:43 and n. 563. Ritual impurity arises from sex pollution.
This is Tayammum, or washing with clean sand or earth where water is not available. I take it that this substitute is permissible both for Wudu' and for a full bath, in the circumstances mentioned.