Sahih al-Bukhari 4966
Book 65: Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh)) · Narrated by Abu Bishr
Arabic
حَدَّثَنَا يَعْقُوبُ بْنُ إِبْرَاهِيمَ، حَدَّثَنَا هُشَيْمٌ، حَدَّثَنَا أَبُو بِشْرٍ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ أَنَّهُ قَالَ فِي الْكَوْثَرِ هُوَ الْخَيْرُ الَّذِي أَعْطَاهُ اللَّهُ إِيَّاهُ. قَالَ أَبُو بِشْرٍ قُلْتُ لِسَعِيدِ بْنِ جُبَيْرٍ فَإِنَّ النَّاسَ يَزْعُمُونَ أَنَّهُ نَهَرٌ فِي الْجَنَّةِ. فَقَالَ سَعِيدٌ النَّهَرُ الَّذِي فِي الْجَنَّةِ مِنَ الْخَيْرِ الَّذِي أَعْطَاهُ اللَّهُ إِيَّاهُ.
English translation
Narrated Abu Bishr:Sa`id bin Jubair said that Ibn `Abbas said about Al-Kauthar. "That is the good which Allah has bestowed upon His Apostle." I said to Sa`id bin Jubair. "But the people claim that it is a river in Paradise." Sa`id said, "The river in Paradise is part of the good which Allah has bestowed on His Apostle
Reference: Sahih al-Bukhari 4966, Book of Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh)). English translation by Dr. Muhammad Muhsin Khan.