Sunan Abi Dawud Book 14, Hadith 160
According to the version of Al Nufaili, A’ishah said “The Prophet (ﷺ) used to pass by a patient while he was observing I’tikaf(in the mosque) but he passed as usual and did not stay asking about him.”
According to the version of Ibn Isa she said “The Prophet (ﷺ) would visit a patient while he was observing I’tikaf.”
The tradition mentioned above has also been transmitted by Al Zuhri through a different chain of narrators. In this version she said “When he was at the gate of the mosque which was near the gate of Umm Salamah, two men passed them. The narrator then transmitted the tradition to the same effect.
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.