Shuʿbah related—from Abū Jamrah (1)—he said: Iyas ibn Qatadah narrated to us, from Qays ibn ʿAbād, who said:
“I came to Madinah in order to meet the Companions of Muhammad ﷺ, and there was no one among them I was more eager to see than Ubayy. The iqāmah (call to commence the prayer) was given and he emerged, so I stood in the first row. A man then arrived, looked at the faces of the worshippers, recognized everyone except me, pushed me aside and stood in my place, and I became so unsettled that I scarcely understood my prayer.
When the prayer ended, he said, ‘My dear son, may Allah never cause you distress. I did not do what I did out of ignorance; rather, the Messenger of Allah ﷺ instructed us, “Stand in the row that is directly behind me.” I looked at the faces of the people and recognized them all except you.’ That man was Ubayy—may Allah be pleased with him. (2)

Al-Dārimī (3) reported: Yaḥyā ibn Ḥassān narrated to us, ʿIkrimah ibn Ibrāhīm narrated to us, Yazīd ibn Shaddād informed us, Muʿāwiyah ibn Qurrah narrated to me, ʿUtbah ibn ʿAbd Allāh ibn ʿAmr ibn al-ʿĀṣ narrated to me, from my father, from my grandfather, who said:
“I was with the Messenger of Allah ﷺ on the day of ʿĪd, and he said, ‘Call for me the leader of the Anṣār.’ So they summoned Ubayy ibn Kaʿb. He said, ‘O Ubayy, go to the Baqīʿ of the prayer-ground and order that it be swept.’” The hadith continues. (4)