Kur’an 31:19 — sura Luqman, 19. ajet

وَٱقۡصِدۡ فِي مَشۡيِكَ وَٱغۡضُضۡ مِن صَوۡتِكَۚ إِنَّ أَنكَرَ ٱلۡأَصۡوَٰتِ لَصَوۡتُ ٱلۡحَمِيرِ

U hodu budi odmjeren, a u govoru ne budi grlat; ta najneprijatniji glas je revanje magarca!"

And be moderate in your pace and lower your voice; indeed, the most disagreeable of sounds is the voice of donkeys