Narrated ‘Amra bint ‘AbdurRahman from ‘Aisha:
Allah’s Apostle mentioned that he would practice Itikaf in the last ten days of Ramadan. ‘Aisha asked his permission to perform Itikaf and he permitted her. Hafsa asked ‘Aisha to take his permission for.
Sahih Bukhari, Volume 3, Book33, Number 261