Anas narrated ‘Verily We have granted you Al-Kauthar’ (108:1) that the Prophet (ﷺ) said: “It is a river in Paradise.” He said: “The Prophet (ﷺ) said: ‘I saw a river in Paradise, whose banks had tents were made of pearl. I said: “What is this O Jibril?’” He said: “This is Al-Kauthar which Allah has granted you.”
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا عَبْدُ بْنُ حُمَيْدٍ، حَدَّثَنَا عَبْدُ الرَّزَّاقِ، عَنْ مَعْمَرٍ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ : ( إناَّ، أَعْطَيْنَاكَ الْكَوْثَرَ ) أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ " هُوَ نَهْرٌ فِي الْجَنَّةِ " . قَالَ فَقَالَ النَّبِيُّ صلى الله عليه وسلم " رَأَيْتُ نَهْرًا فِي الْجَنَّةِ حَافَتَاهُ قِبَابُ اللُّؤْلُؤِ قُلْتُ مَا هَذَا يَا جِبْرِيلُ قَالَ هَذَا الْكَوْثَرُ الَّذِي قَدْ أَعْطَاكَهُ اللَّهُ " . قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ .
sunnah.com