Muwatta Malik #1321
Divorce
The Arabic includes the chain of narration (sanad) and the collector's commentary; the English translation shows the Prophet's words only.
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 " .
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.' "
About Muwatta Malik
This hadith is #1321 from Muwatta Malik, in the Book of Divorce.