It was narrated from 'Aishah that Umm Habibah bint Jahsh who was married to 'Abdur-Rahman bin 'Awf suffered from Istihadah and did not become pure. Her situation was mentioned to the Messenger of Allah (ﷺ) and he said:"That is not menstruation, rather it is a kick in the womb, so let her work out the length of the menses that she used to have, and stop praying (for that period of time), then after that let her perform Ghusl for every for every prayer."
أَخْبَرَنَا الرَّبِيعُ بْنُ سُلَيْمَانَ بْنِ دَاوُدَ بْنِ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا إِسْحَاقُ، - وَهُوَ ابْنُ بَكْرِ بْنِ مُضَرَ - قَالَ حَدَّثَنِي أَبِي، عَنْ يَزِيدَ بْنِ عَبْدِ اللَّهِ، - وَهُوَ ابْنُ أُسَامَةَ بْنِ الْهَادِ - عَنْ أَبِي بَكْرٍ، - وَهُوَ ابْنُ مُحَمَّدِ بْنِ عَمْرِو بْنِ حَزْمٍ - عَنْ عَمْرَةَ، عَنْ عَائِشَةَ، قَالَتْ إِنَّ أُمَّ حَبِيبَةَ بِنْتَ جَحْشٍ الَّتِي كَانَتْ تَحْتَ عَبْدِ الرَّحْمَنِ بْنِ عَوْفٍ وَأَنَّهَا اسْتُحِيضَتْ لاَ تَطْهُرُ فَذُكِرَ شَأْنُهَا لِرَسُولِ اللَّهِ صلى الله عليه وسلم قَالَ " لَيْسَتْ بِالْحِيضَةِ وَلَكِنَّهَا رَكْضَةٌ مِنَ الرَّحِمِ لِتَنْظُرْ قَدْرَ قُرْئِهَا الَّتِي كَانَتْ تَحِيضُ لَهَا فَلْتَتْرُكِ الصَّلاَةَ ثُمَّ تَنْظُرْ مَا بَعْدَ ذَلِكَ فَلْتَغْتَسِلْ عِنْدَ كُلِّ صَلاَةٍ " .
Nesai
The Book of Menstruation and Istihadah • Hadith 356