سنن النسائي

It was narrated from Zainab bint Abi Salamah, from her mother, that a woman came to the Prophet (ﷺ) and asked him about her daughter whose husband had died and she was ill. He said: "One of you used to mourn for a year, then throw a piece of dung when a year had passed. Rather it (the mourning period) is four months and ten days."