Sayyidah Umm Salamah (may Allah be pleased with her) said that the Messenger of Allah (peace and blessings be upon him) said: "Beware! My mosque is forbidden to every man in a state of major impurity (janabah) and every menstruating woman, except Muhammad (peace and blessings be upon him) and his household: Ali, Fatimah, Hasan and Husayn (may Allah be pleased with them)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13402