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darimi:932Muḥammad b. Yūsuf > al-Awzāʿī > Yaḥyá b. Abū Kathīr > Abū Salamah or ʿIkrimah

[Machine] Zainab used to stay in seclusion with the Prophet ﷺ and during her menstrual period, she would bleed. So he instructed her to take a ritual bath after every prayer.  

الدارمي:٩٣٢أَخْبَرَنَا مُحَمَّدُ بْنُ يُوسُفَ حَدَّثَنَا الْأَوْزَاعِيُّ عَنْ يَحْيَى بْنِ أَبِي كَثِيرٍ قَالَ حَدَّثَنِي أَبُو سَلَمَةَ أَوْ عِكْرِمَةُ قَالَ

كَانَتْ زَيْنَبُ تَعْتَكِفُ مَعَ النَّبِيِّ ﷺ وَهِيَ تُرِيقُ الدَّمَ «فَأَمَرَهَا أَنْ تَغْتَسِلَ عِنْدَ كُلِّ صَلَاةٍ»