Quss ibn Sa'ida of Banu Iyad was one of the hunafa', an old man of 80-90 by the time the Prophet ﷺ, then a young man in his twenties, saw him. He would come to Makkah for the hajj and preach against idolatry, and was renowned as one of the most eloquent poets of his time, his language said to resemble that of the Qur'an itself.
When the delegation of Banu Iyad came to Madinah to accept Islam in the 9th year of the Hijrah, about 40 years after the Prophet ﷺ had seen him as a young man, the Prophet ﷺ asked the tribesmen after Quss ibn Sa'ida, the hanif preacher of their tribe. They told him Quss had died long before. The Prophet ﷺ recalled seeing him mounted on a red camel, delivering a mesmerizing speech, and asked if anyone could remind him of it; the tribesmen related the words that had stayed with them, and the Prophet ﷺ approved of what Quss had said.