'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 (ﷺ) of Allah (ﷺ) gave the precise command not to join on prayer till you have engaged in conversation or gone out.

حَدَّثَنَا الْحَسَنُ بْنُ عَلِيٍّ، حَدَّثَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا ابْنُ جُرَيْجٍ، أَخْبَرَنِي عُمَرُ بْنُ عَطَاءِ بْنِ أَبِي الْخُوَارِ، أَنَّ نَافِعَ بْنَ جُبَيْرٍ، أَرْسَلَهُ إِلَى السَّائِبِ بْنِ يَزِيدَ ابْنِ أُخْتِ نَمِرٍ يَسْأَلُهُ عَنْ شَىْءٍ، رَأَى مِنْهُ مُعَاوِيَةُ فِي الصَّلاَةِ فَقَالَ صَلَّيْتُ مَعَهُ الْجُمُعَةَ فِي الْمَقْصُورَةِ فَلَمَّا سَلَّمْتُ قُمْتُ فِي مَقَامِي فَصَلَّيْتُ فَلَمَّا دَخَلَ أَرْسَلَ إِلَىَّ فَقَالَ لاَ تَعُدْ لِمَا صَنَعْتَ إِذَا صَلَّيْتَ الْجُمُعَةَ فَلاَ تَصِلْهَا بِصَلاَةٍ حَتَّى تَكَلَّمَ أَوْ تَخْرُجَ فَإِنَّ نَبِيَّ اللَّهِ صلى الله عليه وسلم أَمَرَ بِذَلِكَ أَنْ لاَ تُوصَلَ صَلاَةٌ بِصَلاَةٍ حَتَّى يَتَكَلَّمَ أَوْ يَخْرُجَ ‏.‏