Narrated Narrated Kathir bin 'Abdullah [and he is Ibn 'Amr bin 'Awf Al-Musani]:

narrated from his father, from his grandfather that the Prophet ﷺ said to Bilal bin Al-Harith: "Know." He said: "I am ready to know O Messenger of Allah!" He ﷺ said: "That indeed whoever revives a Sunnah from my Sunnah which has died after me, then for him is a reward similar to whoever acts upon it without diminishing anything from their rewards. And whoever introduces an erroneous innovation which Allah is not pleased with, nor His Messenger, then he shall receive sins similar to whoever acts upon it, without that diminishing anything from the sins of the people.'"

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ عَبْدِ الرَّحْمَنِ، أَخْبَرَنَا مُحَمَّدُ بْنُ عُيَيْنَةَ، عَنْ مَرْوَانَ بْنِ مُعَاوِيَةَ الْفَزَارِيِّ، عَنْ كَثِيرِ بْنِ عَبْدِ اللَّهِ، عَنْ أَبِيهِ، عَنْ جَدِّهِ، أَنَّ النَّبِيَّ ﷺ قَالَ لِبِلاَلِ بْنِ الْحَارِثِ " اعْلَمْ " . قَالَ مَا أَعْلَمُ يَا رَسُولَ اللَّهِ قَالَ " اعْلَمْ يَا بِلاَلُ " . قَالَ مَا أَعْلَمُ يَا رَسُولَ اللَّهِ قَالَ " أَنَّهُ مَنْ أَحْيَا سُنَّةً مِنْ سُنَّتِي قَدْ أُمِيتَتْ بَعْدِي فَإِنَّ لَهُ مِنَ الأَجْرِ مِثْلَ مَنْ عَمِلَ بِهَا مِنْ غَيْرِ أَنْ يَنْقُصَ مِنْ أُجُورِهِمْ شَيْئًا وَمَنِ ابْتَدَعَ بِدْعَةَ ضَلاَلَةٍ لاَ يَرْضَاهَا اللَّهُ وَرَسُولُهُ كَانَ عَلَيْهِ مِثْلُ آثَامِ مَنْ عَمِلَ بِهَا لاَ يَنْقُصُ ذَلِكَ مِنْ أَوْزَارِ النَّاسِ شَيْئًا " .

قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ . وَمُحَمَّدُ بْنُ عُيَيْنَةَ هُوَ مِصِّيصِيٌّ شَامِيٌّ وَكَثِيرُ بْنُ عَبْدِ اللَّهِ هُوَ ابْنُ عَمْرِو بْنِ عَوْفٍ الْمُزَنِيُّ .