Sunan Ibn Majah 492

Suwaid bin Nu'man Ansari narrated that :They went out with the Messenger of Allah to Khaibar. When they reached As-Sahba' (a place near Khaibar), he performed 'Asr (Afternoon prayer), then he called for food, but no food was brought except for Sawiq. So they ate that and drank, and then he called for water and rinsed his mouth, then he stood up and led us for Maghrib (Sunset) prayer