سورة Luqman 31:19

وَٱقْصِدْ فِى مَشْيِكَ وَٱغْضُضْ مِن صَوْتِكَ ۚ إِنَّ أَنكَرَ ٱلْأَصْوَٰتِ لَصَوْتُ ٱلْحَمِيرِ ١٩

Be moderate in your pace. And lower your voice, for the ugliest of all voices is certainly the braying of donkeys.”