It is narrated from Sayyiduna Suwayd bin al-Nu'man (may Allah be pleased with him) that he set out with the Messenger of Allah (peace and blessings be upon him) in the year of Khaybar, until, when we reached al-Sahba', which is the nearest point to Khaybar, he (peace and blessings be upon him) dismounted and led the Asr prayer. Then he called for the provisions, and nothing was brought except sawiq (barley meal). He (peace and blessings be upon him) gave the order and it was moistened, and the Messenger of Allah (peace and blessings be upon him) ate and we ate too. Then the Messenger of Allah (peace and blessings be upon him) stood up for the Maghrib prayer; he rinsed his mouth and we rinsed our mouths too, then he led the prayer and did not perform fresh ablution. (These are the words of al-Qa'nabi's narration.)
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6426