"We will sell her to you on condition that her loyalty (Walla) is to us," She mentioned that top the Messenger of Allah and he said: "That should not stop you. Loyalty belongs to the one who sets the slave free." (Using translation from Nasāʾī 4644)
أَهْلُهَا نَبِيعُكِ عَلَى أَنَّ وَلَاءَهَا لَنَا فَذَكَرَتْ ذَلِكَ لِرَسُولِ اللهِ ﷺ فَقَالَ لَا يَمْنَعْكِ ذَلِكَ فَإِنَّ الْوَلَاءَ لِمَنْ أَعْتَقَ