Hadith
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، أَنَّ أَسْمَاءَ بِنْتَ عُمَيْسٍ، وَلَدَتْ، مُحَمَّدَ بْنَ أَبِي بَكْرٍ بِذِي الْحُلَيْفَةِ فَأَمَرَهَا أَبُو بَكْرٍ أَنْ تَغْتَسِلَ، ثُمَّ تُهِلَّ .
Yahya related to me from Malik from Yahya ibn Said from Said ibn al-Musayyab that Asma bint Umays gave birth to Muhammad ibn Abi Bakr at Dhu'l-Hulayfa and Abu Bakr told her to do ghusl and then enter ihram
Sahih · Salim al-Hilali
Muwatta Malik 706 ·Book 20, Hadith 2·Also available on sunnah.com·