عَنِ الْمُخْتَارِ بْنِ فُلْفُلٍ رَضِيَ اللَّهُ عَنْهُ قَالَ سَمِعْتُ أَنَسَ بْنَ مَالِكٍ رَضِيَ اللَّهُ عَنْهُ يَقُولُ أَغْفَى النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ إِغْفَاءَةً فَرَفَعَ رَأْسَهُ مُتَبَسِّمًا إِمَّا قَالَ لَهُمْ وَإِمَّا قَالُوا لَهُ لِمَ ضَحِكْتَ فَقَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ إِنَّهُ أُنْزِلَتْ عَلَيَّ آنِفًا سُورَةٌ فَقَرَأَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ إِنَّا أَعْطَيْنَاكَ الْكَوْثَرَ [سورة الكوثر] حَتَّى خَتَمَهَا قَالَ هَلْ تَدْرُونَ مَا الْكَوْثَرُ قَالُوا اللَّهُ وَرَسُولُهُ أَعْلَمُ قَالَ هُوَ نَهَرٌ أَعْطَانِيهِ رَبِّي عَزَّ وَجَلَّ فِي الْجَنَّةِ عَلَيْهِ خَيْرٌ كَثِيرٌ يَرِدُ عَلَيْهِ أُمَّتِي يَوْمَ الْقِيَامَةِ آنِيَتُهُ عَدَدُ الْكَوَاكِبِ يُخْتَلَجُ الْعَبْدُ مِنْهُمْ فَأَقُولُ يَا رَبِّ إِنَّهُ مِنْ أُمَّتِي فَيُقَالُ لِي إِنَّكَ لَا تَدْرِي مَا أَحْدَثُوا بَعْدَكَ
It is narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him) that a drowsiness overcame the Noble Prophet (peace and blessings be upon him), then he (peace and blessings be upon him) raised his head smiling. The people asked: Why are you smiling, O Messenger of Allah (peace and blessings be upon him)? He (peace and blessings be upon him) replied: Just now a surah has been revealed to me. Then he (peace and blessings be upon him) recited {بِسْمِ اللّٰہِ الرَّحْمٰنِ الرَّحِیمِ إِنَّا أَ عْطَیْنَاکَ الْکَوْثَرَ}, until he completed the entire surah, and then said: Do you know what al-Kawthar is? The people said: Allah and His Messenger know best. He (peace and blessings be upon him) said: It is a river which my Lord has granted me in Paradise, in it is much goodness. My ummah will come to me at this river on the Day of Resurrection. Its vessels will be as numerous as the stars, but some people will be prevented from reaching me. I will say: O my Lord! They are from my ummah. It will be said to me: You do not know what they innovated after you.