Al-Wala' (Right of inheritance) belongs to the one who manumits the slave
وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا خَالِدُ بْنُ مَخْلَدٍ، عَنْ سُلَيْمَانَ بْنِ بِلاَلٍ، حَدَّثَنِي سُهَيْلُ بْنُ أَبِي صَالِحٍ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ أَرَادَتْ عَائِشَةُ أَنْ تَشْتَرِيَ، جَارِيَةً تُعْتِقُهَا فَأَبَى أَهْلُهَا إِلاَّ أَنْ يَكُونَ لَهُمُ الْوَلاَءُ فَذَكَرَتْ ذَلِكَ لِرَسُولِ اللَّهِ صلى الله عليه وسلم فَقَالَ " لاَ يَمْنَعُكِ ذَلِكِ فَإِنَّمَا الْوَلاَءُ لِمَنْ أَعْتَقَ " .
Abu Huraira (Allah be pleased with him) reported: 'A'isha (Allah be pleated with her) thought of buying a slave-girl and emancipating her, but her owners refused to (sell her but on the condition) that the right of inheritance would vest in them. She made a mention of that to Allah's Messenger (ﷺ). whereupon he said: Let this (condition) not stand in your way for the right of inheritance vests with one who emancipates.