Sunan Ibn Majah 646
سنن ابن ماجه#646Da'ifIt was narrated from Umm Bakr that:She was told that 'Aishah said: "The Messenger of Allah said concerning a woman who sees that which causes her doubt (i.e. some bleeding) after she becomes pure: 'That is a vein or veins.'" (Da'if)"What was meant by 'after becomes pure' is after having a bath (following the end of her period)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Shuaib Al ArnautSahih Lighairihi
Zubair Ali ZaiDaif
In-book reference: 1:380