Sa'd bin Abu Waqqas (May Allah be pleased with him) reported:
By Allah, I am the first Arab who shot an arrow in the Cause of Allah. We fought along with Messenger of Allah (ﷺ) when our food was only the leaves of Hublah and Samur trees (wild trees) until one of us would defecate like the droppings of sheep.[Al-Bukhari and Muslim].
Arabic/English book reference: Book 1, Hadith 500