Sahih al-Bukhari, Book 70, Hadith 40 (In-Book) ⓘ

Narrated Sa`d: I was one of (the first) seven (who had embraced Islam) with Allah's Messenger and we had nothing to eat then, except the leaves of the Habala or Hubula tree, so that our stool used to be similar to that of sheep. Now the tribe of Bani Asad wants to teach me Islam; I would be a loser and all my efforts would be in vain (if I learn Islam anew from them).

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مُحَمَّدٍ، حَدَّثَنَا وَهْبُ بْنُ جَرِيرٍ، حَدَّثَنَا شُعْبَةُ، عَنْ إِسْمَاعِيلَ، عَنْ قَيْسٍ، عَنْ سَعْدٍ، قَالَ رَأَيْتُنِي سَابِعَ سَبْعَةٍ مَعَ النَّبِيِّ صلى الله عليه وسلم مَا لَنَا طَعَامٌ إِلاَّ وَرَقُ الْحُبْلَةِ ـ أَوِ الْحَبَلَةِ ـ حَتَّى يَضَعَ أَحَدُنَا مَا تَضَعُ الشَّاةُ، ثُمَّ أَصْبَحَتْ بَنُو أَسَدٍ تُعَزِّرُنِي عَلَى الإِسْلاَمِ، خَسِرْتُ إِذًا وَضَلَّ سَعْيِي‏.‏