Qur'an, Hadith and Scholars:What is Allowed to Muhammad and Not to the Ummah

Narrated Aisha: I used to look down upon those ladies who had given themselves to Allah's Apostle and I used to say, "Can a lady give herself (to a man)?" But when Allah revealed: "You (O Muhammad) can postpone (the turn of) whom you will of them (your wives), and you may receive any of them whom you will; and there is no blame on you if you invite one whose turn you have set aside (temporarily).' (33.51) I said (to the Prophet), "I feel that your Lord hastens in fulfilling your wishes and desires."

O ye who believe! Enter not the Prophet's houses,- until leave is given you,- for a meal, (and then) not (so early as) to wait for its preparation: but when ye are invited, enter; and when ye have taken your meal, disperse, without seeking familiar talk. Such (behaviour) annoys the Prophet: he is ashamed to dismiss you, but Allah is not ashamed (to tell you) the truth. And when ye ask (his ladies) for anything ye want, ask them from before a screen: that makes for greater purity for your hearts and for theirs. Nor is it right for you that ye should annoy Allah's Messenger, or that ye should marry his widows after him at any time. Truly such a thing is in Allah's sight an enormity.

O wives of the Prophet! you are not like any other of the women; If you will be on your guard, then be not soft in (your) speech, lest he in whose heart is a disease yearn; and speak a good word.

And stay in your houses and do not display your finery like the displaying of the ignorance of yore; and keep up prayer, and pay the poor-rate, and obey Allah and His Messenger. Allah only desires to keep away the uncleanness from you, O people of the House! and to purify you a (thorough) purifying.

Narrated Jabir bin 'Abdullah:

The Prophet said, "I have been given five things which were not given to any one else before me.
1. Allah made me victorious by awe, (by His frightening my enemies) for a distance of one month's journey.
2. The earth has been made for me (and for my followers) a place for praying and a thing to perform Tayammum, therefore anyone of my followers can pray wherever the time of a prayer is due.
3. The booty has been made Halal (lawful) for me yet it was not lawful for anyone else before me.
4. I have been given the right of intercession (on the Day of Resurrection).

5. Every Prophet used to be sent to his nation only but I have been sent to all mankind.

Narrated 'Aishah: It was narrated that 'Aishah said: "The Messenger of Allah did not die until Allah permitted him to marry whatever women he wanted." (Sahih)