Sayyiduna Imran bin Husayn al-Khuza'i (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) saw a man sitting apart who had not prayed with the people. He (peace and blessings be upon him) said: "O so-and-so! What prevented you from praying with the people?" He said: O Messenger of Allah! I was junub and there was no water. He (peace and blessings be upon him) said: "Hold to the earth, for it is sufficient for you."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1034