It was narrated from 'Adiyy bin Thabit, from his father, from his grandfather, that:
The Prophet said: "The woman who experiences irregular non-menstrual bleeding should leave prayer during the days of her period, then she should take a bath, and perform ablution for each prayer, and she should fast and perform the prayer." (IT)
English reference (IT): Vol. 1, Book 1, Hadith 625 (IT)
Arabic reference (IT): Book 1, Hadith 668 (IT)