Musnad Ahmad 582:0

Narrated to us by Sufyan, from 'Amr, from Sa'ib ibn Yazid, who said: I was standing in the mosque when a pebble was thrown at me. I looked, and it was 'Umar ibn al-Khattab. He said: "Go and bring me those two." So I brought them to him. He said: "Who are you both?" Or: "Where are you both from?" They replied: "We are from the people of Ta'if." He said: "If you had been from the people of this city, I would have surely punished you. You raise your voices in the mosque of the Messenger of Allah (ﷺ)."