Nafi bin Jubayr sent him to Saaib, the nephew of Namir, to ask him about something he had seen Muawiya do in the prayer.He said, "Yes. I prayed the Friday prayer with him in the enclosure. When the imam said the salam, I stood up in my place and prayed. When he went inside, he sent for me and said, 'Do not repeat what you did. When you have prayed the prescribed prayer, do not follow it with another prayer until you have spoken or gone out, for the Messenger of Allah ﷺ commanded us to do this, that we should not join one prayer to another until we speak or go out.'"
أن نافع بن جبير أرسله إلى السائب ابن أخت نمر، يسأله عن شيء رآه معاوية في الصلاة فقال: نعم. صليت معه الجمعة في المقصورة. فلما سلم الإمام قمت في مقامي فصليت، فلما دخل أرسل إلي فقال: لا تعد لما فعلت. إذا صليت الأصبح فلا تصلها بصلاة حتى تكلم أو تخرج فإن رسول الله ﷺ أمرنا بذلك. أن لا توصل صلاة حتى نتكلم، أو نخرج.
Muslim narrated it in the Book of Jumuah (883) from Abu Bakr bin Abu Shayba, and it is in the Musannaf (2/139), Ghundar narrated to us, from Ibn Jurayj, who said, Umar bin Ataa bin Abu al-Khuwar informed me, and he mentioned it.Abdul-Razzaq narrated it in his Musannaf (5534), and from him Abu Dawud (1129) narrated it from Ibn Jurayj with the same wording.In it, Saaib is Ibn Yazid, the nephew of Namir.The maqsurah is the chamber built inside the masjid, which Muawiya introduced after the Kharijite struck him.