Sunan an-Nasa'i 219

It was narrated from 'Aishah that the daughter of Abu Hubaish said:"O Messenger of Allah, I do not become pure, so should I stop praying?" He said: "No, that is a vein." Khalid said, in what I read from him, [1] "And it is not menstruation, so when your period comes, stop praying, and when it goes, wash the blood from yourself and pray." [1] Meaning, before Hisham, from whom he narrates it