And be moderate in your pace and lower your voice; indeed, the most disagreeable of sounds is the voice of donkeys."
The Saheeh International Quran Translation
وَٱقْصِدْ فِى مَشْيِكَ وَٱغْضُضْ مِن صَوْتِكَ إِنَّ أَنكَرَ ٱلْأَصْوَٰتِ لَصَوْتُ ٱلْحَمِيرِAnd be moderate in your pace and lower your voice; indeed, the most disagreeable of sounds is the voice of donkeys."