Musnad Ahmad 1156:31

Yahya ibn Sa'id narrated to us, from Shu'bah, who said: Humayd ibn Nafi' narrated to me, from Zaynab bint Umm Salamah, from her mother, that a woman whose husband had died complained of her eye, so they mentioned her to the Prophet, may Allah bless him and grant him peace, and they mentioned kohl. They said: "We fear for her eye." He said: "One of you used to remain in her house in her worst rags, or in her rags in her worst house, for a year. Then, if a dog passed by her, she would throw a piece of dung at it. Is it not [only] four months and ten [days]?"