Abu Dawud
Purification (Kitab Al-Taharah)
Book Number: 001 / Hadith Number: 335
Narated By Abu Qais, the freed slave of 'Amr b. Al-'As : 'Amr b. al-'As was in a battle. He then narrated the rest of the tradition. He then said: He washed his armpits and other joints where dirt was found, and he performed ablution like that for prayer. Then he led them in prayer. He then narrated the tradition in a simmilar way but did not make a mention pf tayammum.
Abu Dawud said: This incident has also been narrated by al-Awaza'i on the authority of Hassan b. 'Atiyyah. This version has the words: then he performed tayammaum.