حَدَّثَنَا مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا مُحَمَّدٌ، - وَهُوَ ابْنُ جَعْفَرٍ - حَدَّثَنَا شُعْبَةُ، عَنْ عَمْرٍو، قَالَ سَمِعْتُ جَابِرَ بْنَ عَبْدِ اللَّهِ، أَنَّ النَّبِيَّ صلى الله عليه وسلم خَطَبَ فَقَالَ ‏"‏ إِذَا جَاءَ أَحَدُكُمْ يَوْمَ الْجُمُعَةِ وَقَدْ خَرَجَ الإِمَامُ فَلْيُصَلِّ رَكْعَتَيْنِ ‏"‏ ‏.‏

Jabir b. 'Abdullah said that the Messenger of Allah (PBUH) delivered the sermon and said: When any one of you comes for the Friday (prayer) and the Imam comes out (from his apartment), (even then) should observe two rak'ahs (of prayer). Translation Not Available

Book Ref: Sahih Muslim Book 7 Hadith 1901
Web Ref:  Sahih Muslim Book 4 Hadith 875 e