Sahih al-Bukhari 562
Book 9: Times of the Prayers · Narrated by Ibn `Abbas
Arabic
حَدَّثَنَا آدَمُ، قَالَ حَدَّثَنَا شُعْبَةُ، قَالَ حَدَّثَنَا عَمْرُو بْنُ دِينَارٍ، قَالَ سَمِعْتُ جَابِرَ بْنَ زَيْدٍ، عَنِ ابْنِ عَبَّاسٍ، قَالَ صَلَّى النَّبِيُّ صلى الله عليه وسلم سَبْعًا جَمِيعًا وَثَمَانِيًا جَمِيعًا.
English translation
Narrated Ibn `Abbas:The Prophet (ﷺ) prayed seven rak`at together and eight rak`at together
Reference: Sahih al-Bukhari 562, Book of Times of the Prayers. English translation by Dr. Muhammad Muhsin Khan.