Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him), he says: Sayyiduna Abu Dharr (may Allah be pleased with him) was at the place of Rabadhah among his goats. When he returned, the Noble Prophet (peace and blessings be upon him) called out to him: "Abu Dharr!" But he remained silent. The Prophet (peace and blessings be upon him) called out repeatedly, but he remained silent. Finally, the Prophet (peace and blessings be upon him) said: "Abu Dharr! May your mother find you lost." This time he said: I am in a state of janabah (ritual impurity). So the Prophet (peace and blessings be upon him) ordered a slave girl to bring water. When she brought the water, he took cover behind his mount and performed ghusl (ritual bath), and then came to the Prophet (peace and blessings be upon him). The Prophet (peace and blessings be upon him) said to him: "(In such a situation) dust is sufficient for you, even if you do not find water for twenty years or ten years. When you find water, then let it touch your skin (i.e., perform ghusl)."