It is narrated from Sayyiduna Suwayd bin al-Nu'man (may Allah be pleased with him), who was a Companion of the Prophet (peace and blessings be upon him), that he (and the other Companions) set out with the Messenger of Allah (peace and blessings be upon him) towards Khaybar. He said: Until, when we reached al-Sahba', which is a rawhah's distance from Khaybar, the Messenger of Allah (peace and blessings be upon him) called for food, but nothing was found except sawiq (barley meal). We ate it and then drank water after it. Then the Messenger of Allah (peace and blessings be upon him) rinsed his mouth, stood up, and led the prayer.
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6428