The Kitáb-i-Aqdas - The Most Holy Book
Index term: verse to use when water harmful, under Ablutions
n34.
Perform ye . . . ablutions for the Obligatory Prayer
Ablutions are specifically associated with certain prayers. They must precede the offering of the three Obligatory Prayers, the daily recitation of "Alláh-u-Abhá" ninety-five times, and the recital of the verse prescribed as an alternative to obligatory prayer and fasting for women in their courses (see note 20).
The prescribed ablutions consist of washing the hands and the face in preparation for prayer. In the case of the medium Obligatory Prayer, this is accompanied by the recitation of certain verses (see Some Texts Revealed by Bahá'u'lláh Supplementary to the Kitáb-i-Aqdas).
That ablutions have a significance beyond washing may be seen from the fact that even should one have bathed oneself immediately before reciting the Obligatory Prayer, it would still be necessary to perform ablutions (Q&A 18).
When no water is available for ablutions, a prescribed verse is to be repeated five times (see note 16), and this provision is extended to those for whom the use of water would be physically harmful (Q&A 51).
The detailed provisions of the law concerning ablutions are set out in the Synopsis and Codification, section IV.A.10.a.-g., as well as in Questions and Answers numbers 51, 62, 66, 77 and 86.
q51.
 
Question: With reference to ablutions, it hath been revealed, "Let him that findeth no water for ablution repeat five times the words 'In the Name of God, the Most Pure, the Most Pure'": is it permissible to recite this verse in times of bitter cold, or if the hands or face be wounded?
Answer: Warm water may be used in times of bitter cold. If there are wounds on the face or hands, or there be other reasons such as aches and pains for which the use of water would be harmful, one may recite the appointed verse in place of the ablution.