Surah Luqman, Verse 19

وَٱقۡصِدۡ فِي مَشۡيِكَ وَٱغۡضُضۡ مِن صَوۡتِكَۚ إِنَّ أَنكَرَ ٱلۡأَصۡوَٰتِ لَصَوۡتُ ٱلۡحَمِيرِ١٩

wa-iq'ṣid fī mashyika wa-ugh'ḍuḍ min ṣawtika inna ankara l-aṣwāti laṣawtu l-ḥamīri

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