Quran 31:19 from Surah Luqman on Divine Marvels.
وَٱقۡصِدۡ فِي مَشۡيِكَ وَٱغۡضُضۡ مِن صَوۡتِكَۚ إِنَّ أَنكَرَ ٱلۡأَصۡوَٰتِ لَصَوۡتُ ٱلۡحَمِيرِ
English translation: And be moderate in your pace and lower [of] your voice Indeed (the) harshest (of all) sounds (is) surely (the) voice (of) the donkeys
Transliteration: wa-iq'sid fi mashyika wa-ugh'dud min sawtika inna ankara al-aswati lasawtu al-hamiri