Sahih al-Bukhari 841
Sahih al-Bukhari · Book 10: Call to Prayers (Adhaan) · The Dhikr (remembering Allah by Glorifying, Praising and Magnifying Him) after As-Salat (the prayer)
Narrated Abu Ma`bad:
حَدَّثَنَا إِسْحَاقُ بْنُ نَصْرٍ ، قَالَ حَدَّثَنَا عَبْدُ الرَّزَّاقِ ، قَالَ أَخْبَرَنَا ابْنُ جُرَيْجٍ ، قَالَ أَخْبَرَنِي عَمْرٌو ، أَنَّ أَبَا مَعْبَدٍ ، مَوْلَى ابْنِ عَبَّاسٍ أَخْبَرَهُ أَنَّ ابْنَ عَبَّاسٍ ـ رضى الله عنهما ـ أَخْبَرَهُ أَنَّ رَفْعَ الصَّوْتِ بِالذِّكْرِ حِينَ يَنْصَرِفُ النَّاسُ مِنَ الْمَكْتُوبَةِ كَانَ عَلَى عَهْدِ النَّبِيِّ صلى الله عليه وسلم. وَقَالَ ابْنُ عَبَّاسٍ كُنْتُ أَعْلَمُ إِذَا انْصَرَفُوا بِذَلِكَ إِذَا سَمِعْتُهُ .
(the freed slave of Ibn `Abbas) Ibn `Abbas told me, "In the lifetime of the Prophet (ﷺ) it was the custom to celebrate Allah's praises aloud after the compulsory congregational prayers." Ibn `Abbas further said, "When I heard the Dhikr, I would learn that the compulsory congregational prayer had ended."