Umar bin Abi al-Khuwar (may Allah have mercy on him) relates that Nafi' bin Jubayr (may Allah have mercy on him) sent him to Sayyiduna al-Sa'ib bin Yazid (may Allah be pleased with him) to ask him about something that Sayyiduna Mu'awiyah (may Allah be pleased with him) had seen him do in prayer. He said: I prayed the Friday prayer with him in the maqsurah, and when he gave the salam, I stood in my place and began to pray. When he went inside, he sent for me and said: "Do not repeat what you did. When you have prayed the Friday prayer, do not immediately join another prayer to it until you have spoken or gone out, for the Prophet of Allah (peace and blessings be upon him) ordered that." Hawdhah added in his narration: that it should not be joined to another prayer until one has spoken or gone out.
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 16761