It is narrated from Zaynab bint Abi Salamah (may Allah be pleased with her) that when the announcer of the death of Abu Sufyan (may Allah be pleased with him) came, Umm Habibah (may Allah be pleased with her) called for some yellow perfume and, on the third day, applied it to her cheeks and forearms, and said: I would have had no need of this had I not heard the Messenger of Allah (peace and blessings be upon him) say: "It is not permissible for a woman who believes in Allah and the Last Day to mourn for a deceased person for more than three days, except for her husband, for whom she mourns four months and ten days."
Bukhari narrated this hadith.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب العدد / 15518