Shaqiq (may Allah have mercy on him) says that once I was sitting with Hazrat Abu Musa Ash'ari (may Allah be pleased with him) and Hazrat Abdullah bin Mas'ud (may Allah be pleased with him). Hazrat Abu Musa (may Allah be pleased with him) said, "O Abu Abdur Rahman! Tell me, if a person becomes impure and does not find water, should he perform the prayer?" He replied, "No." Hazrat Abu Musa (may Allah be pleased with him) said, "Have you not heard what Hazrat Ammar (may Allah be pleased with him) said, that once the Prophet Muhammad (peace and blessings be upon him) sent me on an errand, and during the journey, I became obliged to perform ghusl (ritual bath), but I did not find water, so I rolled in the earth just as animals do. Then I presented myself before the Prophet Muhammad (peace and blessings be upon him) and mentioned this incident. The Prophet Muhammad (peace and blessings be upon him) said, 'It would have been sufficient for you to do this.' Saying this, the Prophet Muhammad (peace and blessings be upon him) struck his hand on the earth, then wiped both hands together, and then wiped his face." Hazrat Abdullah (may Allah be pleased with him) said, "Do you not know that Hazrat Umar (may Allah be pleased with him) was not satisfied with Hazrat Ammar's (may Allah be pleased with him) statement?" Hazrat Abu Musa (may Allah be pleased with him) said, "Then what about the verse of tayammum?" Hazrat Ibn Mas'ud (may Allah be pleased with him) said, "If we give people this concession, then even in slight cold, they will start performing tayammum."