Abu Rifa reported,

I came to the Prophet ﷺ while he was delivering a sermon. I said, "Messenger of Allah, here is a stranger who has come to ask about his religion, for he does not know what his religion is."The Messenger of Allah ﷺ then turned to me and left off his sermon until he came over to me. A chair was brought, its legs appearing to me to be of iron, and the Messenger of Allah ﷺ sat upon it and began teaching me from what Allah had taught him. Then he returned to his sermon and completed its final portion.

Azami 3321

Sahih

عن أبي رفاعة قال

انتهيت إلى النبي ﷺ وهو يخطب، قال: فقلت: يا رسول الله! رجل غريب جاء يسأل عن دينه، لا يدري ما دينه! قال: فأقبل على رسول الله ﷺ، وترك الخطبة حتى انتهى إلى فأتى بكرسي حسبت قوائمه حديدا، قال: فقعد عليه رسول الله ﷺ، وجعل يعلمني مما علمه الله، ثم أتى خطبته فأتم آخرها.

الأعظمي 3321صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Friday
Chapter
Friday sermon
Section
Permissibility of interrupting the sermon to teach an ignorant person
Numbering
Jami al-Kamil 3321 (2nd edition)
Azami 3321