Sunan Ibn Majah — The Book of Purification and its Sunnah — Hadith No: 625
Translation
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