It is narrated from Sayyidah Umm Atiyyah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) said: "It is not permissible for a woman who believes in Allah and the Last Day to mourn for more than three days, except for a husband," then the narrator mentioned the rest in the same way (as the previous narration).
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 21603