حَدَّثَنَا هَنَّادُ بْنُ السَّرِيِّ، حَدَّثَنَا ابْنُ فُضَيْلٍ، عَنِ الْمُخْتَارِ بْنِ فُلْفُلٍ، قَالَ سَمِعْتُ أَنَسَ بْنَ مَالِكٍ، يَقُولُ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ أُنْزِلَتْ عَلَىَّ آنِفًا سُورَةٌ ‏"‏ ‏.‏ فَقَرَأَ بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ ‏ end actual hadith container 5‏ حَتَّى خَتَمَهَا ‏.‏ قَالَ ‏"‏ هَلْ تَدْرُونَ مَا الْكَوْثَرُ ‏"‏ ‏.‏ قَالُوا اللَّهُ وَرَسُولُهُ أَعْلَمُ ‏.‏ قَالَ ‏"‏ فَإِنَّهُ نَهْرٌ وَعَدَنِيهِ رَبِّي فِي الْجَنَّةِ ‏"‏ ‏.‏

Anas b. Malik said: The Messenger of Allah (PBUH) said: A surah has just been revealed to me. He then recited:”In the name of Allah, the Compassionate, the Merciful. Lo! We have given thee Abundance” until he finished it. Then he asked: Do you know what Abundance (al-Kawthar) is? They replied: Allah and His Apostle know it better. He said: It is a river of which my Lord, the Exalted, the Majestic has promised me to give in Paradise. Translation Not Available

Book Ref: Sunan Abi Dawud Book 2 Hadith 784
Web Ref:  Sunan Abi Dawud Book 2 Hadith 783