Al-Adab Al-Mufrad, Book 44, Hadith 1108 (English) ⓘ

Usama ibn Zayd related that one day the Prophet, may Allah bless him and grant him peace, was riding on a donkey on a straw saddle covered by a blanket from Fadak. Usama ibn Zayd was riding behind him. He was on his way to visit Sa'd ibn 'Ubada. He passed by a meeting which included 'Abdullah ibn Ubayy ibn Salul - before the enemy of Allah had become Muslim. The gathering contained a mixture of Muslims, associaters and idolaters. He greeted them.

حَدَّثَنَا أَبُو الْيَمَانِ، قَالَ‏:‏ أَخْبَرَنَا شُعَيْبٌ، عَنِ الزُّهْرِيِّ قَالَ‏:‏ أَخْبَرَنِي عُرْوَةُ بْنُ الزُّبَيْرِ، أَنَّ أُسَامَةَ بْنَ زَيْدٍ أَخْبَرَهُ، أَنَّ النَّبِيَّ صلى الله عليه وسلم رَكِبَ عَلَى حِمَارٍ عَلَيْهِ إِكَافٌ عَلَى قَطِيفَةٍ فَدَكِيَّةٍ، وَأَرْدَفَ أُسَامَةَ بْنَ زَيْدٍ وَرَاءَهُ، يَعُودُ سَعْدَ بْنَ عُبَادَةَ، حَتَّى مَرَّ بِمَجْلِسٍ فِيهِ عَبْدُ اللهِ بْنُ أُبَيٍّ ابْنُ سَلُولٍ، وَذَلِكَ قَبْلَ أَنْ يُسْلِمَ عَبْدُ اللهِ، فَإِذَا فِي الْمَجْلِسِ أَخْلاَطٌ مِنَ الْمُسْلِمِينَ وَالْمُشْرِكِينَ وَعَبْدَةِ الأَوْثَانِ، فَسَلَّمَ عَلَيْهِمْ‏.‏