Sunan an-Nasa'i
It was narrated that 'Amr bin Dinar said: "I heard Jabir bin 'Abdullah say: 'The Messenger of Allah (ﷺ) said: "If any one of you comes and the Imam has appeared, let him pray two Rak'ahs. Shu'bah (one of the narrators) said: "On Friday."
أَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ الأَعْلَى، قَالَ حَدَّثَنَا خَالِدٌ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ عَمْرِو بْنِ دِينَارٍ، قَالَ سَمِعْتُ جَابِرَ بْنَ عَبْدِ اللَّهِ، يَقُولُ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " إِذَا جَاءَ أَحَدُكُمْ وَقَدْ خَرَجَ الإِمَامُ فَلْيُصَلِّ رَكْعَتَيْنِ " . قَالَ شُعْبَةُ يَوْمَ الْجُمُعَةِ .
Grade: Sahih (Darussalam)
Reference