Sahih Bukhari, Chapter: Prayers (Salat)

I was standing in the mosque and somebody threw a gravel at me. I looked and found that he was 'Umar bin Al-Khattab. He said to me, "Fetch those two men to me." When I did, he said to them, "Who are you? (Or) where do you come from?" They replied, "We are from Ta'if." 'Umar said, "Were you from this city (Medina) I would have punished you for raising your voices in the mosque of Allah's Apostle.