Sunan Ibn Majah 372
سنن ابن ماجه#372Da'ifIt was narrated from Ibn 'Abbas, from Maimunah the wife of the Prophet, that :the Prophet performed ablution with the water left over after she had taken a bath to cleanse herself from sexual impurity
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Shuaib Al ArnautDaif
Zubair Ali ZaiDaif
In-book reference: 1:106