Sahih Bukhari Volume 3, Book 54, Hadith 2727

حَدَّثَنَا خَلاَّدُ بْنُ يَحْيَى، حَدَّثَنَا عَبْدُ الْوَاحِدِ بْنُ أَيْمَنَ الْمَكِّيُّ، عَنْ أَبِيهِ، قَالَ دَخَلْتُ عَلَى عَائِشَةَ ـ رضى الله عنها ـ قَالَتْ دَخَلَتْ عَلَىَّ بَرِيرَةُ وَهْىَ مُكَاتَبَةٌ، فَقَالَتْ يَا أُمَّ الْمُؤْمِنِينَ اشْتَرِينِي فَإِنَّ أَهْلِي يَبِيعُونِي فَأَعْتِقِينِي قَالَتْ نَعَمْ‏.‏ قَالَتْ إِنَّ أَهْلِي لاَ يَبِيعُونِي حَتَّى يَشْتَرِطُوا وَلاَئِي‏.‏ قَالَتْ لاَ حَاجَةَ لِي فِيكِ‏.‏ فَسَمِعَ ذَلِكَ النَّبِيُّ صلى الله عليه وسلم أَوْ بَلَغَهُ، فَقَالَ ‏"‏ مَا شَأْنُ بَرِيرَةَ فَقَالَ اشْتَرِيهَا فَأَعْتِقِيهَا وَلْيَشْتَرِطُوا مَا شَاءُوا ‏"‏‏.‏ قَالَتْ فَاشْتَرَيْتُهَا فَأَعْتَقْتُهَا، وَاشْتَرَطَ أَهْلُهَا وَلاَءَهَا، فَقَالَ النَّبِيُّ صلى الله عليه وسلم ‏"‏ الْوَلاَءُ لِمَنْ أَعْتَقَ، وَإِنِ اشْتَرَطُوا مِائَةَ شَرْطٍ ‏"‏‏.‏

Narrated By Aiman Al-Makki : When I visited 'Aisha she said, "Buraira who had a written contract for her emancipation for a certain amount came to me and said, 'O mother of the believers! Buy me and manumit me, as my masters will sell me.'" 'Aisha agreed to it. Buraira said, "My masters will sell me on the condition that my Wala' will go to them." 'Aisha said to her, "Then I am not in need of you. "The Prophet heard of that or was told about it and so he asked 'Aisha, "What is the problem of Buraira? "He said, "Buy her and manumit her, no matter what they stipulate." 'Aisha added, "I bought and manumitted her, though her masters had stipulated that her Wala' would be for them." The Prophet said, "The Wala' is for the liberator, even if the other stipulated a hundred conditions."