Sayyidah Fatimah al-Kubra (may Allah be pleased with her) said: The Messenger of Allah (peace and blessings be upon him) said: "All the children of a mother are attributed to some agnatic kin ('asabah), except the children of Fatimah; I am their guardian and I am their 'asabah."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2619