Sahih Bukhari
Ablutions (Wudu)
Volume: 001 / Book Number: 004 / Hadith Number: 213
Narrated 'Amr bin 'Amir:
Anas said, "The Prophet used to perform ablution for every prayer." I asked Anas, "What you used to do?' Anas replied, "We used to pray with the same ablution until we break it with Hadath."