بُلُوغُ الْمَرَامِ
Bulugh al-Maram 1063
Marriage
وَعَنْهَا قَالَتْ : { كَانَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -إِذَا أَرَادَ سَفَرًا أَقْرَعَ بَيْنَ نِسَائِهِ , فَأَيَّتُهُنَّ خَرَجَ سَهْمُهَا , خَرَجَ بِهَا } مُتَّفَقٌ عَلَيْه ِ [1] .
Narrated ['Aishah (RA)]: When Allah's Messenger (ﷺ) intended to go on a journey, he cast lots among his wives. Then, he would take with him the one who was chosen by the lot. [Agreed upon].
Sunnah.com reference: Book 8, Hadith 112