'A'isha (RAA) narrated, 'It is Sunnah for the one performing I'tikaf not to visit the sick, attend a funeral, or touch his wife (with sexual desire), nor have sexual intercourse with her. He should also not go out (of the mosque) except for an extreme necessity, and no I'tikaf is accepted without fasting, or without being in a congregational mosque (where Friday prayer is performed).' Related by Abu Dawud with an acceptable chain of narrators, but scholars say that the last part (starting:
'no I'tikaf is accepted….) is most probably the saying of 'A'isha (RAA), i.e. Hadith Mauquf (i.e. that which the companion does not connect to the Prophet and it is not the Prophet (ﷺ) himself.
English reference: Book 5, Hadith 722
Arabic reference: Book 5, Hadith 702