That he heard a man reciting a Quranic Verse which he had heard the Prophet ﷺ reciting in a different way. So he took that man to the Prophet (and told him the story). The Prophet ﷺ said, "Both of you are reciting in a correct way, so carry on reciting." The Prophet ﷺ further added, "The nations which were before you were destroyed (by Allah) because they differed."
سَمِعَ النَّبِيَّ ﷺ خِلاَفَهَا فَأَخَذْتُ بِيَدِهِ فَانْطَلَقْتُ بِهِ إِلَى النَّبِيِّ ﷺ فَقَالَ كِلاَكُمَا مُحْسِنٌ فَاقْرَآ أَكْبَرُ عِلْمِي قَالَ فَإِنَّ مَنْ كَانَ قَبْلَكُمُ اخْتَلَفُوا فَأَهْلَكَهُمْ