Hadith 16.1
Marriage
Umm Habiba and Zainab daughter of Jahsh reported God’s Messenger as saying, “It is not lawful for a woman who believes in God and the last day to observe mourning for one who has died more than three nights, except for the four months and ten days in the case of a husband.” (Bukhari and Muslim.)
وَعَنْ أُمِّ حَبِيبَةَ وَزَيْنَبَ بِنْتِ جحش عَنْ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «لَا يَحِلُّ لِامْرَأَةٍ تُؤْمِنُ بِاللَّهِ وَالْيَوْمِ الْآخِرِ أَنْ تُحِدَّ عَلَى مَيِّتٍ فَوْقَ ثَلَاثِ لَيَالٍ إِلَّا عَلَى زَوْجٍ أَرْبَعَةَ أَشْهُرٍ وَعَشْرًا»
Hadith gradings, numbering and translations can differ between editions. For legal rulings or detailed interpretation, consult qualified scholarship and the referenced edition.