Whilst describing the circumstances of departing for military campaigns with the Holy Prophet (sa), Hazrat Sa‘d (ra) states, “We would leave for a battle together with the Holy Prophet (sa) and our condition would be such that we would not have anything available to eat except leaves of trees. Our condition was such that our passing of stool resembled the droppings of a camel or goat.”
In other words, it was very dry and not soft at all. In another narration it is mentioned that he said, “Our food in those days used to be the branches of a Babul tree.” Babul is a type of tree that has many thorny branches.
(Sahih al-Bukhari, Kitab-ul-Fazail al-Sahaba al-Nabi, Hadith no. 3728), (Jami’ Tirmidhi, Abwaab-ul-Zuhd, Hadith no. 2366)