Narrated `Imran bin Husain Al-Khuza`i: Allah's Apostle saw a person sitting aloof and not praying with the people. He asked him, O so and so! What prevented you from offering the prayer with the people? He replied, O Allah's Apostle! I am Junub and there is no water. The Prophet said, Perform Tayammum with clean earth and that will be sufficient for you.