The Messenger of Allah ﷺ said, "Clean earth is the means of purification for a Muslim, even if he does not find water for ten years. But when he finds water, let him touch it to his skin, for that is better."
قال رسول الله ﷺ: الصعيد الطيب وضوء المسلم، وإن لم يجد الماء عشر سنين، فإذا وجده فليمسه بشره، فإن ذلك خير.
It was narrated by Abu Dawud (332), Tirmidhi (124), Nasai (322), and Ahmad (21568), all of them from the hadith of Abu Qilaba, from Amr bin Bujdan, from Abu Dharr, and he related it, and the wording given is Ahmad's. Its chain of transmission is hasan due to the discussion concerning Amr bin Bujdan, as was detailed earlier in the book on tayammum, and Tirmidhi said, "hasan sahih."