"From her mother?" He said: "Yes" - "that the Prophet was asked about a woman whose husband had died but they were worried about her eyes - could she use kohl?" He said: "One of you used to stay in her house wearing her shabbiest clothes for a year, then she would come out. No, (the mourning period is) four months and ten (days)."
Sunan an-Nasa'i Book 27, Hadith 113
← Previous Hadith "Umm Habibah said: 'I heard the Messenger of Allah say: It is not permissible for a woman who believes in Allah and the Last Day to mourn for anyone who dies for more than three days, except for a husband; (she mourns for him for) four months and ten (days)."

Sunan an-Nasa'i Book 27, Hadith 112 Next Hadith → "A woman came to the Prophet and said: 'My daughter's husband has died, and I am worried about her eyes. Can I apply kohl to her?' The Messenger of Allah said: 'One of you used to stay (in mourning) for a year. Rather (the mourning period is) four months and ten (days). And when that year had passed she would go out and fling a piece of dung behind her.'"

Sunan an-Nasa'i Book 27, Hadith 114