Hadithcore
Bulugh al-Maram, 139

In the narration of Asma bint ‘Umais, Abu Dawud transmitted, (the Prophet (ﷺ) said:

) "She should sit in a tub, and if she sees yellowness appearing (on top of the water) she should wash (three times), once for the Dhuhr and Asr prayers, and once for the Maghrib and Isha prayers, and once for the Fajr prayer, and she should then perform ablution in between those times."

وَفِي حَدِيثِ أَسْمَاءَ بِنْتِ عُمَيْسٍ عِنْدَ أَبِي دَاوُدَ: { لِتَجْلِسْ فِي مِرْكَنٍ, فَإِذَا رَأَتْ صُفْرَةً فَوْقَ اَلْمَاءِ, فَلْتَغْتَسِلْ لِلظُّهْرِ وَالْعَصْرِ غُسْلاً وَاحِدًا, وَتَغْتَسِلْ لِلْمَغْرِبِ وَالْعِشَاءِ غُسْلاً وَاحِدًا, وَتَغْتَسِلْ لِلْفَجْرِ غُسْلاً, وَتَتَوَضَّأْ فِيمَا بَيْنَ ذَلِكَ } [1]‏ .‏

References2 variants
In-Book Reference
Book 1, Hadith 168
English Reference
Book 1, Hadith 150