Hadith 507080
Chapter 20: Hajj - كتاب الحج
حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ الْقَاسِمِ، عَنْ أَبِيهِ، عَنْ أَسْمَاءَ بِنْتِ عُمَيْسٍ، أَنَّهَا وَلَدَتْ مُحَمَّدَ بْنَ أَبِي بَكْرٍ بِالْبَيْدَاءِ فَذَكَرَ ذَلِكَ أَبُو بَكْرٍ لِرَسُولِ اللَّهِ صلى الله عليه وسلم فَقَالَ " مُرْهَا فَلْتَغْتَسِلْ ثُمَّ لِتُهِلَّ " .
Yahya related to me from Malik from Abd ar-Rahman ibn al-Qasim from his father from Asma bint Umays that she gave birth to Muhammad ibn Abi Bakr at al-Bayda. Abu Bakr mentioned this to the Messenger of Allah, may Allah bless him and grant him peace, and he said, "Tell her to do ghusl and then enter ihram."
Reference Muwatta Malik 507080
USC-MSA web (English) reference : Book 20, Hadith 1