Sunan An-Nasai, Chapter: The Book of Purification

from his father that a man came to Umar and said: "I have become Junub and I do not have any water." Umar said: "Do not pray." But 'Ammar bin Yasir said: "O Commander of the Believers! Don't you remember when you and I were on a campaign and we became Junub and could not find water? You did not pray, but I rolled in the dust and prayed. Then we came to the Prophet (saw) and told him about that, and he said: 'It would have been sufficient for you (to do this),' then the Prophet (saw) struck his hands on the ground and blew on them, then wiped his face and hands with them'" - (one of the narrators) Salamah was uncertain and did not know whether that was up to the elbows or just the hands. And Umar said: "We will let you bear the burden of what you took upon yourself." (Sahih)