exempted from this those who are weak from illness or age, as a bounty from His Presence, and He is the Forgiving, the Generous. God hath granted you leave to prostrate yourselves on any surface that is clean, for We have removed in this regard the limitation that had been laid down in the Book; God, indeed, hath knowledge of that whereof ye know naught. Let him that findeth no water for ablution repeat five times the words “In the Name of God, the Most Pure, the Most Pure”, and then proceed to his devotions. Such is the command of the Lord of all worlds. In regions where the days and nights grow long, let times of prayer be gauged by clocks and other instruments that mark the passage of the hours. He, verily, is the Expounder, the Wise.