Muwatta Malik #233
Jumu'a
The Arabic includes the chain of narration (sanad) and the collector's commentary; the English translation shows the Prophet's words only.
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، رَأَى رَجُلَيْنِ يَتَحَدَّثَانِ وَالإِمَامُ يَخْطُبُ يَوْمَ الْجُمُعَةِ فَحَصَبَهُمَا أَنِ اصْمُتَا .
Yahya related to me from Malik from Nafi that Abdullah ibn Umar
saw two men talking while the imam was giving the khutba on the day of
jumua and he threw pebbles at them to tell them to be quiet.
About Muwatta Malik
This hadith is #233 from Muwatta Malik, in the Book of Jumu'a.