Zaynab bint Umm Salama reported,

Then I visited Zaynab bint Jahsh when her brother died. She called for perfume and applied some of it, then said, "By Allah, I have no need for perfume, except that I heard the Messenger of Allah ﷺ say from the pulpit, 'It is not lawful for a woman who believes in Allah and the Last Day to mourn for any deceased person beyond three days, except for a husband, for whom she mourns four months and ten days.'"

Muslim 3726

Sahih

قالت زينب

ثم دخلت على زينب بنت جحش حين توفي أخوها فدعت بطيب فمست منه ثم قالت والله ما لي بالطيب من حاجة غير أني سمعت رسول الله ﷺ يقول على المنبر لا يحل لامرأة تؤمن بالله واليوم الآخر تحد على ميت فوق ثلاث إلا على زوج أربعة أشهر وعشرا

مسلم 3726صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Muslim
Book
Divorce
Chapter
Obligation of mourning restrictions during the waiting period after a husband's death and its prohibition otherwise except for three days
Numbering
Darussalam 3726
Muslim 3726