Sunan Ibn Majah — The Chapters on Marriage — Hadith No: 2000
Translation
It 'was narrated from Hisham bin 'Urwah, from his father that 'Aishah used to say:"Wouldn't a woman feel too shy to offer herself to the Prophet?" Until Aileh revealed; "You (O Muhammad) can postpone (the turn of) whom you will of them (your wives), and you may receive whom you will.” She said: "Then I said: 'Your Lord is quick to make things easy for you