Sahih Muslim
The Book Pertaining to the Merits of the Companions (Allah Be Pleased With Them) of the Holy Prophet (May Peace Be Upon Him) (Kitab Al-Fadail Al-Sahabah)
Book Number: 031 / Hadith Number: 6000
Miswar b. Makhramah reported Allah's Messenger (may peace be upon him) as saying: Fatima is a part of me. He in fact tortures me who tortures her.