كتاب الحج
15  
The Book of Pilgrimage
(49)
Chapter: It is recommended to send the weak among women and others ahead from Al-Muzdalifah to Mina at the end of the night, before it gets crowded, but it is recommended for others to stay there until they have prayed Subh in Al-Muzdalifah
(49)
باب اسْتِحْبَابِ تَقْدِيمِ دَفْعِ الضَّعَفَةِ مِنَ النِّسَاءِ وَغَيْرِهِنَّ مِنْ مُزْدَلِفَةَ إِلَى مِنًى فِي أَوَاخِرِ اللَّيَالِي قَبْلَ زَحْمَةِ النَّاسِ وَاسْتِحْبَابِ الْمُكْثِ لِغَيْرِهِمْ حَتَّى يُصَلُّوا الصُّبْحَ بِمُزْدَلِفَةَ
Sahih Muslim 1290 b

A'isha (Allah be pleased with her) reported that (hadrat) Sauda was a bulky lady, so she sought permission from Allah's Messenger (ﷺ) to proceed from Muzdalifa (to Mina) in the (latter part of the) night. He granted her permission. 'A'isha said:

I wish I had also sought permission from Allah's Messenger (ﷺ) as Sauda had. sought permission from him. 'A'isha did not proceed but with the Imam.
وَحَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، وَمُحَمَّدُ بْنُ الْمُثَنَّى، جَمِيعًا عَنِ الثَّقَفِيِّ، - قَالَ ابْنُ الْمُثَنَّى حَدَّثَنَا عَبْدُ الْوَهَّابِ، - حَدَّثَنَا أَيُّوبُ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ الْقَاسِمِ، عَنِ الْقَاسِمِ، عَنْ عَائِشَةَ، قَالَتْ كَانَتْ سَوْدَةُ امْرَأَةً ضَخْمَةً ثَبِطَةً فَاسْتَأْذَنَتْ رَسُولَ اللَّهِ صلى الله عليه وسلم أَنْ تُفِيضَ مِنْ جَمْعٍ بِلَيْلٍ فَأَذِنَ لَهَا فَقَالَتْ عَائِشَةُ فَلَيْتَنِي كُنْتُ اسْتَأْذَنْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم كَمَا اسْتَأْذَنَتْهُ سَوْدَةُ وَكَانَتْ عَائِشَةُ لاَ تُفِيضُ إِلاَّ مَعَ الإِمَامِ ‏.‏
Reference : Sahih Muslim 1290b
In-book reference : Book 15, Hadith 323
USC-MSA web (English) reference : Book 7, Hadith 2959
  (deprecated numbering scheme)