Asma bint Umays gave birth at Shajarah, so the Messenger of Allah ﷺ instructed Abu Bakr to tell her to perform the ritual bath and enter the state of ihram.
حدثنا عثمان بن أبي شيبة حدثنا عبدة بن سليمان عن عبيد الله عن عبد الرحمن بن القاسم عن أبيه
نفست أسماء بنت عميس بالشجرة فأمر رسول الله ﷺ أبا بكر أن يأمرها أن تغتسل وتهل
Muslim narrated it in "Hajj," in the chapter on the validity of the ihram of a woman in postpartum bleeding and the recommendation of her performing ghusl for ihram, as is the case for a menstruating woman, hadith no. 1209, from Uthman bin Abu Shayba, with this chain.