وَاقْصِدْ فِي مَشْيِكَ وَاغْضُضْ مِنْ صَوْتِكَ ۚ إِنَّ أَنْكَرَ الْأَصْوَاتِ لَصَوْتُ الْحَمِيرِ 19
"And be moderate in thy pace, and lower thy voice; for the harshest of sounds without doubt is the braying of the ass."