It was sufficient for you to do this with your hands." Then, he struck the ground once with his hands, then wiped the right hand with the left one, the back side of his hands and his face

The Prophet (may Allah's peace and blessings be upon him) sent 'Ammār ibn Yāsir (may Allah be pleased with him) on an errand. 'Ammār became in a state of Janābah (major ritual impurity), either because of sexual intercourse or the discharge of semen upon sexual arousal, and could not find water to take a ritual bath. He did not know the ruling on performing Tayammum (dry ablution) for Janābah; however, he knew its ruling for minor Hadath (ritual impurity).

Based on his Ijtihād (personal reasoning), he thought that just as dirt on the surface of the earth is used to wipe some of the body parts of ablution in case of minor Hadath, then performing Tayammum from Janābah must be done by comprehending the entire body with dirt, in analogy to water. So, he rolled in dirt until it reached his whole body and then prayed. On coming to the Prophet (may Allah's peace and blessings be upon him), he mentioned it to see whether his actions were right.

The Prophet (may Allah's peace and blessings be upon him) clarified to him the manner of attaining purity from minor Hadath like urine and from major Hadath like Janābah, namely by striking dirt with his hands once, then wiping the right hand with the left one, as well as the back side of his hands and face.