Sahih Muslim
The Book of Pilgrimage (Kitab Al-Hajj)
Book Number: 007 / Hadith Number: 2762
A'isha (Allah be pleased with her) reported that Asma' hint 'Umais gave birth to Muhammad b Abu Bakr near Dhu'I-Hulaifa. The Messenger of Allah (may peace be upon him) commanded Abu Bakr to convey to her that she should take a bath and then enter into the state of Ihram.