Muwatta Imam Malik Book of Hajj, Hadith 184

Yahya related to me from Malik from Hisham ibn Urwa that Fatima bint al-Mundhir told him that she used to see Asma bint Abi Bakrat Muzdalifa telling whoever led the subh prayer for her and her companions to pray it as soon as the dawn broke, after which she would mount and go to Mina without stopping at all.

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ فَاطِمَةَ بِنْتِ الْمُنْذِرِ، أَخْبَرَتْهُ أَنَّهَا، كَانَتْ تَرَى أَسْمَاءَ بِنْتَ أَبِي بَكْرٍ بِالْمُزْدَلِفَةِ تَأْمُرُ الَّذِي يُصَلِّي لَهَا وَلأَصْحَابِهَا الصُّبْحَ يُصَلِّي لَهُمُ الصُّبْحَ حِينَ يَطْلُعُ الْفَجْرُ ثُمَّ تَرْكَبُ فَتَسِيرُ إِلَى مِنًى وَلاَ تَقِفُ .