Ash-Shama'il Al-Muhammadiyah, Book 50, Hadith 355 (English) ⓘ

Sa'd bin Abi Waqqias Radiyallahu 'Anhu reports that from the ummah of Muhammad Sallallahu 'Alayhi Wasallam I was the first to take the blood of a non-believer, and I was the first to shoot an arrow in the path of Allah.We (the group of Sahaabah in the early period of Islaam) went for jihaad in such a state, where we had nothing to eat. We ate the leaves of tree and pods of the acacia tree. As a result our jaw became ulcerous and wounded, and because of the leaves our excreta was like that of sheep and camel. After that too the people of Banu Asad threatened me. If the status of my ignorance in the deen is such as these people claim, then this world and the hereafter is lost. (The days in this world have been spent in poverty and difficulty, and the state of the deen is this that I do not have knowledge of salaah too).

حدثنا عمر بن إسماعيل بن مجالد بن سعيد، حدثني أبي عن بيان حدثني قيس بن حازم، قال‏:‏ سمعت سعد بن أبي وقاص يقول‏:‏ إني لأَوْل رَجل أَهْرَقَ دَمًا فِي سَبِيلِ اللهِ ‏,‏ وَإِنْي لأَوْل رَجلٍ رَمَى بِسَهْمٍ فِى سَبِيلِ اللهِ َلقَدْ رَأَيْتُنِي أغزوا فِي الْعِصَابَةَ مِنْ أَصْحَابِ مُحَمْدٍ صلى الله عليه وسلم مَا نَأكُلْ إلاَّ وَرَقَ الشَجَرِ وَالْحُبْلَةَ حَتَّى تَقَرَحَتْ أَشْدَاقُنَا وَإِنْ أَحَدُنَا لَيَضَعُ كَمَا تَضَعُ الشَّاةُ وَالبَعِير وَأَصْبَحَتْ بَنُو أَسَدٍ يَعَزِّرُونَنِى فِي الدِّينِ ‏,‏ لَقَدْ خِبْتُ إذَنْ وَخَسِرْت وَضَلَ عَمَلِي‏.‏‏.‏