Musannaf Ibn Abi Shayba 1:1356

Jarir narrated to us, from Mansur, from Ibrahim, who said: She shall sit for the days of her menstruation during which she used to menstruate. When those days have passed, she shall perform ghusl. Then she shall delay the Dhuhr and hasten the Asr, and pray them both with one ghusl, each one of them in its [proper] time. Then she shall perform ghusl for the Maghrib and the Isha, and she shall delay the Maghrib and hasten the Isha, and then pray each one of them in its [proper] time. Then she shall perform ghusl for the Fajr.