Sahih Bukhari Volume 6, Book 60, Hadith Number 311.

Narrated By 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.”