(73) باب إِذَا اشْتَرَطَ شُرُوطًا فِي الْبَيْعِ لاَ تَحِلُّ
Narrated `Abdullah bin `Umar:
Aisha, (mother of the faithful believers) wanted to buy a slave girl and manumit her, but her masters said that they would sell her only on the condition that her Wala' would be for them. `Aisha told Allah's Messenger (ﷺ) of that. He said, "What they stipulate should not hinder you from buying her, as the Wala' is for the manumitted."
Reference: Sahih al-Bukhari 2169
In-book reference: Book 34, Hadith 120
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 3, Book 34, Hadith 378