Muwatta Malik, Book 29, Hadith 102 (USC-MSA) ⓘ

Zaynab said, "I went to the house of Zaynab bint Jahsh, the wife of the Prophet, may Allah bless him and grant him peace, when her brother had died. She called for perfume and put some on and said, 'By Allah! I have no need of perfume, but I heard the Messenger of Allah, may Allah bless him and grant him peace, say, 'It is not halal for a woman who trusts in Allah and the Last Day to abstain from adornment in mourning for someone who has died for more than three nights, except for four months and ten days for a husband.' "

قَالَتْ زَيْنَبُ ثُمَّ دَخَلْتُ عَلَى زَيْنَبَ بِنْتِ جَحْشٍ زَوْجِ النَّبِيِّ صلى الله عليه وسلم حِينَ تُوُفِّيَ أَخُوهَا فَدَعَتْ بِطِيبٍ فَمَسَّتْ مِنْهُ ثُمَّ قَالَتْ وَاللَّهِ مَا لِي بِالطِّيبِ حَاجَةٌ غَيْرَ أَنِّي سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ ‏ "‏ لاَ يَحِلُّ لاِمْرَأَةٍ تُؤْمِنُ بِاللَّهِ وَالْيَوْمِ الآخِرِ تُحِدُّ عَلَى مَيْتٍ فَوْقَ ثَلاَثِ لَيَالٍ إِلاَّ عَلَى زَوْجٍ أَرْبَعَةَ أَشْهُرٍ وَعَشْرًا ‏" ‏ ‏.‏