It was narrated from Shabib Abi Rawh, from a man among the companions of the Prophet (ﷺ), that: He prayed Subh and recited Ar-Rum, but he stumbled in his recitation. When he had finished praying he said: 'What is the matter with people who pray with us without purifying themselves properly? Those people make us stumble in reciting Quran.'"
Source: sunnah.com
Other translations
Arabic
أَخْبَرَنَا مُحَمَّدُ بْنُ بَشَّارٍ، قَالَ حَدَّثَنَا عَبْدُ الرَّحْمَنِ، قَالَ أَنْبَأَنَا سُفْيَانُ، عَنْ عَبْدِ الْمَلِكِ بْنِ عُمَيْرٍ، عَنْ شَبِيبٍ أَبِي رَوْحٍ، عَنْ رَجُلٍ، مِنْ أَصْحَابِ النَّبِيِّ صلى الله عليه وسلم عَنِ النَّبِيِّ صلى الله عليه وسلم أَنَّهُ صَلَّى صَلاَةَ الصُّبْحِ فَقَرَأَ الرُّومَ فَالْتَبَسَ عَلَيْهِ فَلَمَّا صَلَّى قَالَ " مَا بَالُ أَقْوَامٍ يُصَلُّونَ مَعَنَا لاَ يُحْسِنُونَ الطُّهُورَ فَإِنَّمَا يَلْبِسُ عَلَيْنَا الْقُرْآنَ أُولَئِكَ " .
sunnah.com