I say, and with God's success: It is for one who has lost water and soil, as in being confined in a place that is impure and cannot obtain pure soil, and likewise for one who is unable to do so due to illness. He must resemble the praying individuals by necessity, so he should bow and prostrate if he finds a dry place; otherwise, he should gesture while standing and then repeat the prayer. This is what is issued in fatwas; for Ibn Umar (may Allah be pleased with him) reported that the Prophet (peace be upon him) said: "Prayer is not accepted without purification, nor is charity from ill-gotten gains," in Sahih Muslim 1: 204, and Sahih Bukhari 1: 63. Refer to: Al-Durr Al-Mukhtar and Rad Al-Muhtar 252-253, and Allah knows best.