Sunan an-Nasa'i, Volume 6, Book 48, Hadith 5379 (DarusSalam) ⓘ

It was narrated that Humaid bin Hilal said: "Abu Rifa'ah said: 'I came to the Messenger of Allah [SAW] while he was delivering a Khutbah, and said: "O Messenger of Allah, a stranger has come to ask about his religion, for he does not know what his religion is." The Messenger of Allah [SAW] stopped delivering his Khutbah and turned to me. A chair was brought, and I think its legs were of iron. The Messenger of Allah [SAW] sat down on it and started to teach me what Allah has taught him, then he went and completed his Khutbah.'"

أَخْبَرَنَا يَعْقُوبُ بْنُ إِبْرَاهِيمَ، عَنْ عَبْدِ الرَّحْمَنِ، عَنْ سُلَيْمَانَ بْنِ الْمُغِيرَةِ، عَنْ حُمَيْدِ بْنِ هِلاَلٍ، قَالَ قَالَ أَبُو رِفَاعَةَ انْتَهَيْتُ إِلَى رَسُولِ اللَّهِ صلى الله عليه وسلم وَهُوَ يَخْطُبُ فَقُلْتُ يَا رَسُولَ اللَّهِ رَجُلٌ غَرِيبٌ جَاءَ يَسْأَلُ عَنْ دِينِهِ لاَ يَدْرِي مَا دِينُهُ فَأَقْبَلَ رَسُولُ اللَّهِ صلى الله عليه وسلم وَتَرَكَ خُطْبَتَهُ حَتَّى انْتَهَى إِلَىَّ فَأُتِيَ بِكُرْسِيٍّ خِلْتُ قَوَائِمَهُ حَدِيدًا فَقَعَدَ عَلَيْهِ رَسُولُ اللَّهِ صلى الله عليه وسلم فَجَعَلَ يُعَلِّمُنِي مِمَّا عَلَّمَهُ اللَّهُ ثُمَّ أَتَى خُطْبَتَهُ فَأَتَمَّهَا ‏.‏