Musannaf Ibn Abi Shaybah 1013 — Purity after menstruation: what it

Fatimah bint al-Mundhir said: We were under the care of Sayyidah Asma bint Abi Bakr (may Allah be pleased with her) along with her daughter's daughters. Sometimes one of us girls would become pure and pray, and then she would notice a little yellow discharge, so we asked Sayyidah Asma about it. She said: "Leave the prayer until you see pure whiteness."