It is narrated from Sayyiduna Sa'd bin Malik (may Allah be pleased with him): I saw myself as the seventh of seven with the Messenger of Allah (peace and blessings be upon him); we had nothing to eat except the leaves of trees. This is how Shu'bah narrated it. And each one of us would pass droppings like a goat. Then Banu Asad came to reproach me concerning Islam; in that case I would indeed have suffered loss and my effort would have gone to waste.
(b) In the narration of Ibn Uyaynah: they ate the leaves of trees or a bean-like plant, and all of us would pass droppings like a goat.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 519