Sunan an-Nasa'i, Volume 3, Book 24, Hadith 2762 (DarusSalam) ⓘ

It was narrated that Jabir bin 'Abdullah said: "The Messenger of Allah stayed for nine years during which he did not perform Hajj. Then it was announced among the people the he was going for Hajj. No one who was able to come riding or on foot stayed behind, and the people rushed to go out with him until he came to Dhul-Hulaifah. Asam' bint 'Umais gave birth to Muhammad bin Abi Bakr and she sent word to the messenger of Allah (Asking what she should do). He said: 'Perform Ghusl and wrap a cloth around your private parts, then begin the Talbiyah.' So she did that." An abridgment

أَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ عَبْدِ الْحَكَمِ، عَنْ شُعَيْبٍ، أَنْبَأَنَا اللَّيْثُ، عَنِ ابْنِ الْهَادِ، عَنْ جَعْفَرِ بْنِ مُحَمَّدٍ، عَنْ أَبِيهِ، عَنْ جَابِرِ بْنِ عَبْدِ اللَّهِ، قَالَ أَقَامَ رَسُولُ اللَّهِ صلى الله عليه وسلم تِسْعَ سِنِينَ لَمْ يَحُجَّ ثُمَّ أَذَّنَ فِي النَّاسِ بِالْحَجِّ فَلَمْ يَبْقَ أَحَدٌ يَقْدِرُ أَنْ يَأْتِيَ رَاكِبًا أَوْ رَاجِلاً إِلاَّ قَدِمَ فَتَدَارَكَ النَّاسُ لِيَخْرُجُوا مَعَهُ حَتَّى جَاءَ ذَا الْحُلَيْفَةِ فَوَلَدَتْ أَسْمَاءُ بِنْتُ عُمَيْسٍ مُحَمَّدَ بْنَ أَبِي بَكْرٍ فَأَرْسَلَتْ إِلَى رَسُولِ اللَّهِ صلى الله عليه وسلم فَقَالَ ‏ "‏ اغْتَسِلِي وَاسْتَثْفِرِي بِثَوْبٍ ثُمَّ أَهِلِّي ‏" ‏ ‏.‏ فَفَعَلَتْ مُخْتَصَرٌ ‏.‏