"Then I went into Zainab bint Jahsh when her brother died, and she called for some perfume and put some on. Then she said: 'By Allah, I do not have any need for perfume but I heard the Messenger of Allah say on the Minbar: It is not permissible for any woman who believes in Allah and the Last Day to mourn for anyone who dies for more than three days, except for a husband, (for whom the mourning period is) four months and ten days.'"
Sunan an-Nasa'i Book 27, Hadith 146
← Previous Hadith "I entered upon Umm Habibah, the wife of the Prophet, when her father Abu Sufyan bin Harb died. Umm Habibah called for some perfume and put some on a young girl, then she put some on her cheeks. Then she said: 'By Allah, I do not have any need for perfume but I heard the Messenger of Allah say: It is not permissible for any woman who believes in Allah and the Last Day to mourn for anyone who dies for more than three days, except for a husband, (for whom the mourning period is) four months and ten days.'"

Sunan an-Nasa'i Book 27, Hadith 145 Next Hadith → "I heard Umm Salamah say: 'A woman came to the Messenger of Allah and said: O Messenger of Allah, my daughter's husband has died and she has a problem in her eye; can I put kohl on her? The Messenger of Allah said: No. Then he said: It is four months and ten days. During the Jahiliyyah one of you would throw a piece of dung at the end of the year.'" Humaid said: "I said to Zainab: 'What is this throwing a piece of dung at the end of the year?' She said: 'If a woman's husband died, she would enter a small room (Hifsh) and wear her worst clothes, and she would not put on perfume or anything until a year. Then an animal would be brought, a donkey or sheep or bird, and she would end her 'Iddah with it (clean herself with it), and usually any animal used for that purpose would die. Then she would come out and would be given a piece of dung which she would throw, then she would go back to whatever she wanted of perfume, etc.'" In the narration of Muhammad (bin Salamah) Malik said: Hifsh means hut.

Sunan an-Nasa'i Book 27, Hadith 147