Hadith 4:817
Abu Usamah narrated to us, from Hisham, from al-Hasan, regarding a man who had intercourse with his wife while he was in I'tikaf: He is in the position of the one who had intercourse during Ramadan; upon him is what is upon the one who had intercourse during Ramadan.
حدثنا أبو أسامة عن هشام عن الحسن في رجل غشي امرأته وهو معتكف أنه بمنزلة الذي غشي في رمضان عليه ما على الذي أصاب في رمضان