Mishkat al-Masabih 2212
Ibn Mas’ūd said:
I heard a man who recited, and as I had heard the Prophet reciting differently I took him to the Prophet and told him and noticed that he gave a disapproving look. He then said, “Both of you are doing it well, so do not disagree, for your predecessors disagreed and perished.” 

Bukhārī transmitted it.
وَعَنِ ابْنِ مَسْعُودٍ رَضِيَ اللَّهُ عَنْهُ قَالَ: سَمِعْتُ رَجُلًا قَرَأَ وَسَمِعْتُ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقْرَأُ خِلَافَهَا فَجِئْتُ بِهِ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَأَخْبَرْتُهُ فَعَرَفْتُ فِي وَجهه الْكَرَاهِيَة فَقَالَ: «كِلَاكُمَا مُحْسِنٌ فَلَا تَخْتَلِفُوا فَإِنَّ مَنْ كَانَ قبلكُمْ اخْتلفُوا فهلكوا» . رَوَاهُ البُخَارِيّ