Musnad Abu Ya'la al-Mawsili 150:121

Bishr ibn al-Walid narrated to us, Abu Aqil Yahya ibn al-Mutawakkil narrated to us, from Bahiyyah, that she heard a woman asking Aisha about a woman whose menstruation had become irregular, so she did not know how to pray. Aisha said to her: "I asked the Messenger of Allah (ﷺ) about a woman whose menstruation had become irregular and who was bleeding profusely, and she did not know how to pray. The Messenger of Allah (ﷺ) commanded me to instruct her to look at the duration she used to menstruate each month when her menstruation was regular, and to sit for that same number of nights and days, then to leave the prayer during them and estimate them. Then, she should perform ghusl for her period of purity, then bind herself with a cloth, then pray. For I hope that this is from Satan, and that Allah will remove it from her, if Allah wills." She said: "So I instructed her to do that, and Allah removed it from her. So instruct your companion to do that."