Musannaf Ibn Abi Shayba 3:3123

Waki’ narrated to us, from Sufyan ibn al-Sa’ib, from Salih ibn Sa’id, who said: I went out with Umar ibn Abd al-Aziz to al-Suwayda’ as a traveler. When the time for Friday prayer arrived, the caller to prayer gave the adhan, and they gathered pebbles for him. He said: So he stood up and delivered the sermon, then he prayed the Friday prayer as two rak'ahs. Then he said: "The Imam performs the Friday prayer wherever he may be."