كتاب الصلاة
4  
The Book of Prayers
(30)
Chapter: Women Going Out To The Masjid So Long As No Fitnah Results From That; and They Should Not Go Out Wearing Perfume
(30)
باب خُرُوجِ النِّسَاءِ إِلَى الْمَسَاجِدِ إِذَا لَمْ يَتَرَتَّبْ عَلَيْهِ فِتْنَةٌ وَأَنَّهَا لاَ تَخْرُجُ مُطَيَّبَةً
Sahih Muslim 442 d

lbn Umar reported:

I heard the Messeinger of Allah (ﷺ) say: When your women seek your permission for going to the mosque, you grant them (permission).
حَدَّثَنَا ابْنُ نُمَيْرٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا حَنْظَلَةُ، قَالَ سَمِعْتُ سَالِمًا، يَقُولُ سَمِعْتُ ابْنَ عُمَرَ، يَقُولُ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ ‏ "‏ إِذَا اسْتَأْذَنَكُمْ نِسَاؤُكُمْ إِلَى الْمَسَاجِدِ فَأْذَنُوا لَهُنَّ ‏"‏ ‏.‏
Reference : Sahih Muslim 442d
In-book reference : Book 4, Hadith 153
USC-MSA web (English) reference : Book 4, Hadith 887
  (deprecated numbering scheme)