Surat Luqman (Luqman) - لقمان

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

And pursue the right course in your going about and lower your voice; surely the most hateful of voices is braying of the asses.