Narrated `Aisha:I bought Barirah but her masters put the condition that her Wala' would be for them. I told the Prophet (ﷺ) about it. He said (to me), "Manumit (free) her as her Wala' will be for the one who pays the price." So, I manumitted (freed) her. The Prophet (ﷺ) called Barirah and gave her the option of either staying with her husband or leaving him. She said, "Even if he gave me so much money, I would not stay with him," and so she preferred her freedom to her husband.
حَدَّثَنَا عُثْمَانُ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا جَرِيرٌ، عَنْ مَنْصُورٍ، عَنْ إِبْرَاهِيمَ، عَنِ الأَسْوَدِ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ قَالَتِ اشْتَرَيْتُ بَرِيرَةَ فَاشْتَرَطَ أَهْلُهَا وَلاَءَهَا، فَذَكَرْتُ ذَلِكَ لِلنَّبِيِّ صلى الله عليه وسلم فَقَالَ " أَعْتِقِيهَا، فَإِنَّ الْوَلاَءَ لِمَنْ أَعْطَى الْوَرِقَ ". فَأَعْتَقْتُهَا، فَدَعَاهَا النَّبِيُّ صلى الله عليه وسلم فَخَيَّرَهَا مِنْ زَوْجِهَا فَقَالَتْ لَوْ أَعْطَانِي كَذَا وَكَذَا مَا ثَبَتُّ عِنْدَهُ. فَاخْتَارَتْ نَفْسَهَا.
Bukhari
Manumission of Slaves • Hadith 20