Malik related to me from Nafi from Abdullah ibn Umar that A'isha umm al-muminin wanted to buy a slave-girl and set her free. Her people said, "We will sell her to you provided that her wala' is ours." She mentioned that to the Messenger of Allah ﷺ and he said, "Don't let that hinder you, for the wala' only belongs to the one who sets free."
أَنَّ وَلاَءَهَا لَنَا فَذَكَرَتْ ذَلِكَ لِرَسُولِ اللَّهِ ﷺ فَقَالَ لاَ يَمْنَعَنَّكِ ذَلِكَ فَإِنَّمَا الْوَلاَءُ لِمَنْ أَعْتَقَ