(13) Marriage
كتاب النكاح
(9a) Chapter: Sharing Visits to one’s Wives Equally - Section 1
(9) باب القسم - الفصل الأول
Mishkat al-Masabih 3232 
She said that when God’s Messenger intended to go on a journey he cast lots among his wives and the one who was chosen by lot went on it with him. (Bukhari and Muslim.)
وَعَنْهَا قَالَتْ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِذَا أَرَادَ سَفَرًا أَقْرَعَ بَيْنَ نِسَائِهِ فأيهن خَرَجَ سَهْمُهَا خَرَجَ بِهَا مَعَهُ
 مُتَّفَقٌ عَلَيْهِ  (الألباني)حكم :
Reference : Mishkat al-Masabih 3232
In-book reference : Book 13, Hadith 150