Musannaf Ibn Abi Shayba 3:3050

Ghundar narrated to us, from Ibn Jurayj, who said: 'Umar ibn 'Ata' ibn Abi al-Khuwar informed me that Nafi' ibn Jubayr sent him to al-Sa'ib ibn Yazid, the nephew of Namir, to ask him about something Mu'awiyah had seen him do during prayer. He said: "Yes, I prayed Jumu'ah with him in the Maqsura. When the Imam finished the salutation, I stood in my place and prayed. When he (Mu'awiyah) entered, he sent for me and said: 'Do not repeat what you did. When you pray Jumu'ah, do not connect it with another prayer until you speak or leave, for the Messenger of Allah (peace and blessings of Allah be upon him) commanded us regarding that: that one prayer should not be connected to another until one speaks or leaves.'"