Sahih Bukhari Volume 7, Book 63, Hadith Number 257.

Narrated By Zainab bint Um Salama : When Um Habiba bint Abi Sufyan was informed of her father’s death, she asked for perfume and rubbed it over her arms and said, “I am not in need of perfume, but I have heard the Prophet saying, “It is not lawful for a lady who believes in Allah and the Last Day to mourn for more than three days except for her husband for whom the (mourning) period is four months and ten days.”