It was narrated from 'Urwah bin Zubair that Fatimah bint Abi Hubaish narrated to him that:
She went to the Messenger of Allah and complained to him about bleeding. The Messenger of Allah said: "Rather that is a vein, so look and see when your period comes, then do not perform the prayer. When the period is over, then purify yourself and perform the prayer between one period to the next."

حَدَّثَنَا مُحَمَّدُ بْنُ رُمْحٍ، أَنْبَأَنَا اللَّيْثُ بْنُ سَعْدٍ، عَنْ يَزِيدَ بْنِ أَبِي حَبِيبٍ، عَنْ بُكَيْرِ بْنِ عَبْدِ اللَّهِ، عَنِ الْمُنْذِرِ بْنِ الْمُغِيرَةِ، عَنْ عُرْوَةَ بْنِ الزُّبَيْرِ، أَنَّ فَاطِمَةَ بِنْتَ أَبِي حُبَيْشٍ، حَدَّثَتْهُ أَنَّهَا، أَتَتْ رَسُولَ اللَّهِ ـ ﷺ ـ فَشَكَتْ إِلَيْهِ الدَّمَ فَقَالَ رَسُولُ اللَّهِ ـ ﷺ ـ " إِنَّمَا ذَلِكَ عِرْقٌ فَانْظُرِي إِذَا أَتَى قَرْؤُكِ فَلاَ تُصَلِّي فَإِذَا مَرَّ الْقَرْءُ فَتَطَهَّرِي ثُمَّ صَلِّي مَا بَيْنَ الْقَرْءِ إِلَى الْقَرْءِ " .