'Umar b. 'Ata' b. Abu al-Khuwar said that Nafi' b. Jubair sent him to al-Sa'ib b. Yazid b. Ukht Namir to ask him about something Mu'awiyyah had seen him do in prayer. He said: I offered the Friday prayer along with him in enclosure. When I uttered the salutation I stood up in my place and prayed. When he went in, he sent me a message saying: Never again do what you have done. When you pray the Friday prayer, you must not join another prayer to it till you have engaged in conversation or gone out, for the Prophet of Allah (ﷺ) gave the precise command not to join on prayer till you have engaged in conversation or gone out.