Sunan an-Nasa'i 3541

It was narrated from Zainab that a woman asked Umm Salamah and Umm Habibah whether she could put on kohl during her 'Iddah following her husband's death. She said:"A woman came to the Prophet and asked him about that, and he said: 'During the Jahiliyyah, if her husband died, one of you would stay (in mourning) for a year, then she would throw a piece of dung then come out. Rather it (the mourning period) is four months and ten days, until the term prescribed is fulfilled