It is narrated from Sayyidah Umm Habibah (may Allah be pleased with her) that when a close relative of hers died, she took some yellow perfume, applied it to her forearms and said: The Messenger of Allah (peace and blessings be upon him) said: "It is not permissible for a Muslim woman who believes in Allah and the Hereafter to mourn for a deceased person for more than three days, except for her husband; she mourns for him four months and ten days."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب العدد / 15519