Narrated Aishah, Ummul Muminin: The sunnah for one who is observing Itikaf (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 Itikaf without fasting, and there is no Itikaf except in a congregational mosque.
Hadith Referenceسنن ابي داود / كتاب الصيام / 2473
Hadith Gradingالألبانی:حسن صحيح | زبیر علی زئی:إسناده صحيح, الزھري صرح بالسماع عند الطبراني في مسند الشاميين (2910)
Benefits and Issues: Both narrations mentioned in this chapter are weak. Therefore, only those matters stated in it are correct which are established by other authentic narrations, and the other matters are not authentic.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 2473