Sahih al-Bukhari 5125
In-book no 5125وَسَمِعْتُ زَيْنَبَ ابْنَةَ أُمِّ سَلَمَةَ، تُحَدِّثُ عَنْ أُمِّ حَبِيبَةَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ " لاَ يَحِلُّ لاِمْرَأَةٍ مُسْلِمَةٍ تُؤْمِنُ بِاللَّهِ وَالْيَوْمِ الآخِرِ أَنْ تُحِدَّ فَوْقَ ثَلاَثَةِ أَيَّامٍ، إِلاَّ عَلَى زَوْجِهَا أَرْبَعَةَ أَشْهُرٍ وَعَشْرًا ".
Narrated Um Habiba: The Prophet (ﷺ) said, "It is not lawful for a Muslim woman who believes in Allah and the Last Day to mourn for more than three days, except for her husband, for whom she should mourn for four months and ten days."