Sahih Muslim Book 42, Hadith Number 7077.
Chapter : Not known.
Khalid b. Umair reported: I heard Uqba b. Ghazwan as saving: I found myself as the seventh amongst the seven who had been along with Allah’s Messenger (may peace be upon him).We had nothing to eat but the leaves of hubla (a wild tree) until the corners of our mouths were injured.