"Or you have had contact with women." Al-mulamasa (contact) in the view of Ali, Ibn Abbas, and al-Hasan is sexual intercourse. Ibn Mas'ud used to say it is touching with the hand, and he maintained that it requires wudu (ablution). "Then seek clean soil and wipe over your faces and your hands [with it]." That is: Intend clean earth. "And wipe your faces and your hands."
Yahya [narrated] from al-Mu'alla, from Abu Ishaq al-Hamdani, from Najiya ibn Ka'b, from Ammar ibn Yasir, who said: "I became in a state of janaba while I was among the camels, so I rolled in the sand just as a beast rolls. Then I came to the Prophet, peace be upon him, with sand in my head and beard, and I informed him. He said: 'It would have been sufficient for you to perform tayammum.' Then the Prophet, peace be upon him, struck the earth with both his palms together, then shook them off, then wiped his face and his palms once. Then he said: 'It would have been sufficient for you to do like this.'" And Yahya adopts this view.