Abu Dawud
Fasting
Book Number: 007 / Hadith Number: 2467
Narated By 'Aisha, Ummul Mu'minin : The sunnah for one who is observing i'tikaf (in a mosque) is not to visit a patient, or to attend a funeral, or touch or embrace one's wife, or go out for anything but necessary purposes. There is no i'tikaf without fasting, and there is no i'tikaf except in a congregational mosque.