Messenger of Allah ﷺ forbade the selling or donating the Wala' of a freed slave.  

سَمِعْتُ ابْنَ عُمَرَ ؓ يَقُولُ نَهَى رَسُولُ اللَّهِ ﷺ عَنْ بَيْعِ الْوَلاَءِ وَعَنْ هِبَتِهِ  

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.  

قَالَتِ اشْتَرَيْتُ بَرِيرَةَ فَاشْتَرَطَ أَهْلُهَا وَلاَءَهَا فَذَكَرْتُ ذَلِكَ لِلنَّبِيِّ ﷺ فَقَالَ أَعْتِقِيهَا فَإِنَّ الْوَلاَءَ لِمَنْ أَعْطَى الْوَرِقَ فَأَعْتَقْتُهَا فَدَعَاهَا النَّبِيُّ ﷺ فَخَيَّرَهَا مِنْ زَوْجِهَا فَقَالَتْ لَوْ أَعْطَانِي كَذَا وَكَذَا مَا ثَبَتُّ عِنْدَهُ فَاخْتَارَتْ نَفْسَهَا