From Bukhari as well as Muslim:
From Hadrat Abu Hujaifa (RA) it is narrated that I found the Rasool Ullah
(Sall Allah Ho ALaihe Wa Aalihee Wa Sallam) in a red lather tent . and saw
that Hadrat Bilal(Raddi Allah Ho Ta Ala Anho) was holding the used water
from the wudu of the Rasool Ullah (Sall Allah Ho Alaihe Wa Aalihee Wa
Sallam) and people were extrending their hands towards the water. So whoever
got the water, he rubbed it on his body while whoever did not get it, he got
the wetness from his companion's hand.