Be not forward in the presence of Allah and His messenger [Muhammad] ... Lift not up your voices above the voice of the Prophet, nor shout when speaking to him as ye shout one to another. 49:1-2
Lo! they who subdue their voices in the presence of the messenger of Allah [Muhammad], those are they whose hearts Allah hath proven unto righteousness. Theirs will be forgiveness and immense reward. 49:3
Lo! those who call thee [Muhammad] from behind the private apartments, most of them have no sense. 49:4
Let not a folk deride a folk ... neither defame one another, nor insult one another by nicknames. 49:11
Spy not, neither backbite one another. Would one of you love to eat the flesh of his dead brother? 49:12
Say (unto them, O Muhammad): Would ye teach Allah your religion? 49:16