Sahih al-Bukhari 2138
Narrated Aisha:
Rarely did the Prophet (ﷺ) fail to visit Abu Bakr's house everyday, either in the morning or in the evening. 
When the permission for migration to Medina was granted, all of a sudden the Prophet (ﷺ) came to us at 
noon and Abu Bakr was informed, who said, "Certainly the Prophet (ﷺ) has come for some urgent 
matter." The Prophet (ﷺ) said to Abu Bark, when the latter entered "Let nobody stay in your home." Abu 
Bakr said, "O Allah's Messenger (ﷺ)! There are only my two daughters (namely `Aisha and Asma') present." 
The Prophet (ﷺ) said, "I feel (am informed) that I have been granted the permission for migration." Abu 
Bakr said, "I will accompany you, O Allah's Messenger (ﷺ)!" The Prophet (ﷺ) said, "You will accompany me." 
Abu Bakr then said "O Allah's Messenger (ﷺ)! I have two she-camels I have prepared specially for migration, 
so I offer you one of them. The Prophet (ﷺ) said, "I have accepted it on the condition that I will pay its 
price."
حَدَّثَنَا فَرْوَةُ بْنُ أَبِي الْمَغْرَاءِ، أَخْبَرَنَا عَلِيُّ بْنُ مُسْهِرٍ، عَنْ هِشَامٍ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ قَالَتْ لَقَلَّ يَوْمٌ كَانَ يَأْتِي عَلَى النَّبِيِّ صلى الله عليه وسلم إِلاَّ يَأْتِي فِيهِ بَيْتَ أَبِي بَكْرٍ أَحَدَ طَرَفَىِ النَّهَارِ، فَلَمَّا أُذِنَ لَهُ فِي الْخُرُوجِ إِلَى الْمَدِينَةِ لَمْ يَرُعْنَا إِلاَّ وَقَدْ أَتَانَا ظُهْرًا، فَخُبِّرَ بِهِ أَبُو بَكْرٍ فَقَالَ مَا جَاءَنَا النَّبِيُّ صلى الله عليه وسلم فِي هَذِهِ السَّاعَةِ، إِلاَّ لأَمْرٍ حَدَثَ، فَلَمَّا دَخَلَ عَلَيْهِ قَالَ لأَبِي بَكْرٍ ‏"‏ أَخْرِجْ مَنْ عِنْدَكَ ‏"‏‏.‏ قَالَ يَا رَسُولَ اللَّهِ إِنَّمَا هُمَا ابْنَتَاىَ‏.‏ يَعْنِي عَائِشَةَ وَأَسْمَاءَ‏.‏ قَالَ ‏"‏ أَشَعَرْتَ أَنَّهُ قَدْ أُذِنَ لِي فِي الْخُرُوجِ ‏"‏‏.‏ قَالَ الصُّحْبَةَ يَا رَسُولَ اللَّهِ‏.‏ قَالَ ‏"‏ الصُّحْبَةَ ‏"‏‏.‏ قَالَ يَا رَسُولَ اللَّهِ إِنَّ عِنْدِي نَاقَتَيْنِ أَعْدَدْتُهُمَا لِلْخُرُوجِ، فَخُذْ إِحْدَاهُمَا‏.‏ قَالَ ‏"‏ قَدْ أَخَذْتُهَا بِالثَّمَنِ ‏"‏‏.‏