It is reported from Al-Faḍl b. Mūsā that he said:
ʿAbdullāh b. Al-Mubārak and I once came to a bridge, so I said to him, “Go ahead”, and he said, “Go ahead.” So we calculated [the age difference], and it turned out I was two years older than him.
Al-Khaṭīb, Al-Jāmiʿ li Akhlāq Al-Rāwī #249.
Al-Khaṭīb mentions after these and other narrations,“And if the elder gives precedence to someone more knowledgeable than himself, this is allowed, and it is good.”
He then reports that Al-Ḥusayn b. Manṣūr said:
One day, I was with Yaḥyā b. Yaḥyā and Isḥāq (Ibn Rāhuwayh) visiting a sick person. When we all came to the door (next to each other), Isḥāq stepped back and said to Yaḥyā, “Go ahead.” Yaḥyā said to Isḥāq, “You go ahead.” He replied, “O Abū Zakarīyah, you are older than me.” Yaḥyā replied, “Yes, I am older than you, but you are more knowledgeable than me.” So Isḥāq went ahead.
Op. cit. #252.