31:19
وَٱقْصِدْ فِى مَشْيِكَ وَٱغْضُضْ مِن صَوْتِكَ ۚ إِنَّ أَنكَرَ ٱلْأَصْوَٰتِ لَصَوْتُ ٱلْحَمِيرِ
wa-iq'ṣid fī mashyika wa-ugh'ḍuḍ min ṣawtika inna ankara l-aṣwāti laṣawtu l-ḥamīri
Go at a moderate pace and lower your voice, for the ugliest of all voices is the braying of asses.’
"And be moderate (or show no insolence) in your walking, and lower your voice. Verily, the harshest of all voices is the braying of the asses."