Sahih al-Bukhari 2410
Narrated `Abdullah:
I heard a man reciting a verse (of the Holy Qur'an) but I had heard the Prophet (ﷺ) reciting it differently. 
So, I caught hold of the man by the hand and took him to Allah's Messenger (ﷺ) who said, "Both of you are 
right." Shu`ba, the sub-narrator said, "I think he said to them, "Don't differ, for the nations before you 
differed and perished (because of their differences). "
حَدَّثَنَا أَبُو الْوَلِيدِ، حَدَّثَنَا شُعْبَةُ، قَالَ عَبْدُ الْمَلِكِ بْنُ مَيْسَرَةَ أَخْبَرَنِي قَالَ سَمِعْتُ النَّزَّالَ، سَمِعْتُ عَبْدَ اللَّهِ، يَقُولُ سَمِعْتُ رَجُلاً، قَرَأَ آيَةً سَمِعْتُ مِنَ النَّبِيِّ، صلى الله عليه وسلم خِلاَفَهَا، فَأَخَذْتُ بِيَدِهِ، فَأَتَيْتُ بِهِ رَسُولَ اللَّهِ صلى الله عليه وسلم فَقَالَ ‏"‏ كِلاَكُمَا مُحْسِنٌ ‏"‏‏.‏ قَالَ شُعْبَةُ أَظُنُّهُ قَالَ ‏"‏ لاَ تَخْتَلِفُوا فَإِنَّ مَنْ كَانَ قَبْلَكُمُ اخْتَلَفُوا فَهَلَكُوا ‏"‏‏.‏