Narrated Suwaid bin Nu’man:
In the year of the conquest of Khaibar I went with Allah’s Apostle till we reached As-Sahba’ where Allah’s Apostle led the ‘Asr prayer and asked for the food. Nothing but Sawiq was brought and we ate it and drank (water). The Prophet got up for the (Maghrib) Prayer, rinsed his mouth with water and then led the prayer without repeating the ablution.
Sahih Bukhari, Volume 1, Book4, Number 214