Sahih Muslim Book - 20, Hadith - 3776

وَحَدَّثَنَا يَحْيَى بْنُ يَحْيَى قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ عَنْ عَائِشَةَ أَنَّهَا أَرَادَتْ أَنْ تَشْتَرِىَ جَارِيَةً تُعْتِقُهَا فَقَالَ أَهْلُهَا نَبِيعُكِهَا عَلَى أَنَّ وَلاَءَهَا لَنَا. فَذَكَرَتْ ذَلِكَ لِرَسُولِ اللَّهِ -صلى الله عليه وسلم- فَقَالَ « لاَ يَمْنَعُكِ ذَلِكَ فَإِنَّمَا الْوَلاَءُ لِمَنْ أَعْتَقَ ».

It was narrated from 'Aishah that she wanted to buy a slave woman and manumit her, and her masters said: "We will sell her on condition that the right of inheritance (Al-Wala') remains ours." She mentioned that to the Messenger of Allah (s.a.w) and he said: "Do not let that stop you, for the right of inheritance belongs to the one who manumits (the slave)."