Rubbing hands and feet with dust (Tayammum)

Bukhari :: Book 1 :: Volume 7 :: Hadith 336

Narrated 'Abdur Rahman bin Abza:

that while he was in the company of 'Umar, 'Ammar said to 'Umar, "We were in a detachment and became Junub and I blew the dust off my hands (performed the rolling over the earth and prayed.)"