The Book of Divorce
18/9. Chapter:
The Obligation to mourn during the 'Iddah following the death of one's husband, but it is forbidden to mourn for more than three days in other cases
Sahih Muslim
وَحَدَّثَتْهُ زَيْنَبُ، عَنْ أُمِّهَا، وَعَنْ زَيْنَبَ، زَوْجِ النَّبِيِّ صلى الله عليه وسلم أَوْ عَنِ امْرَأَةٍ مِنْ بَعْضِ أَزْوَاجِ النَّبِيِّ صلى الله عليه وسلم .
This hadith was narrated by Zainab from her mother and from Zainab, the wife of Allah's Apostle (ﷺ), or from some other lady from among the wives of the Prophet (ﷺ).
Reference : Sahih Muslim 1487, 1488bIn-book reference : Book 18, Hadith 75USC-MSA web (English) reference : Book 9, Hadith 3540