Musnad Ahmad 1566

Qais told us: I heard Sa"d bin Malik say: I was the first of the Arabs to shoot an arrow for the sake of Allah. There was a time when we would go out on campaign with the Messenger of Allah (ﷺ) and we would have no food except the leaves of al-hublah and as-samur (desert trees), and one of us would produce stools like a sheep, so dry that nothing would stick to it. And now Banu Asad are teaching me about my religion, in which case I must have been doomed and my efforts wasted.