Is it permissible to sleep while in a state of major ritual impurity (janabah) and wake up to perform ghusl before Fajr prayer?

It is permissible for a person in a state of ritual impurity (junub) to sleep before performing ghusl, and then to perform ghusl before the Fajr prayer. This is based on the statement of 'Aisha: "The Messenger of Allah, peace and blessings be upon him, used to sleep while he was junub and would not touch water." It is better for him to perform ablution (wudu') before sleeping, and if he performs ghusl, that is more complete. This is based on 'Aisha's statement: "He used to do all of that; sometimes he would perform ghusl and then sleep, and sometimes he would perform wudu' and then sleep." And 'Umar asked the Prophet, peace and blessings be upon him: "Can one of us sleep while he is junub?" He said: "Yes, if he performs wudu'."