(And be moderate in your pace) just as in His saying: (And do not walk on the earth insolently). (And lower your voice; indeed, the most disagreeable of sounds) meaning: the ugliest (is the voice of donkeys).

Muhammad said: The meaning of (aghḍuḍ - lower) is: reduce. The meaning is that He informed him of the ugliness of raising one's voice during conversation and arguing by comparing it to the ugliness of the voices of donkeys, because they are loud.

Surat Luqman, from verse 20 to verse 22.