Sahih Muslim 324
Sahih Muslim · Book 3: The Book of Menstruation · The amount of water with which it is recommended to perform ghusl in the case of janabah; a man and woman washing from a single vessel; one of them washing with the left-over water of the other
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى ، حَدَّثَنَا مُعَاذُ بْنُ هِشَامٍ ، قَالَ حَدَّثَنِي أَبِي ، عَنْ يَحْيَى بْنِ أَبِي كَثِيرٍ ، حَدَّثَنَا أَبُو سَلَمَةَ بْنُ عَبْدِ الرَّحْمَنِ ، أَنَّ زَيْنَبَ بِنْتَ أُمِّ سَلَمَةَ ، حَدَّثَتْهُ أَنَّ أُمَّ سَلَمَةَ حَدَّثَتْهَا قَالَتْ، كَانَتْ هِيَ وَرَسُولُ اللَّهِ صلى الله عليه وسلم يَغْتَسِلاَنِ فِي الإِنَاءِ الْوَاحِدِ مِنَ الْجَنَابَةِ .
Zainab bint Umm Salama (the wife of the Holy Prophet) reported that Umm Salama and the Messenger of Allah (ﷺ) took a bath from the same vessel.