Sahih Bukhari Volume 001, Book 005, Hadith Number 252.
Narated By Abu Ja'far : While I and my father were with Jabir bin 'Abdullah, some People asked him about taking a bath He replied, "A Sa' of water is sufficient for you." A man said, "A Sa' is not sufficient for me." Jabir said, "A Sa was sufficient for one who had more hair than you and was better than you (meaning the Prophet)." And then Jabir (put on) his garment and led the prayer.