Sahih Al Bukhari (453)

عن عائشة قالت {أتتها بريرة تسألها في كتابتها فقالت إن شئت أعطيت أهلك ويكون الولاء لي وقال أهلها إن شئت أعطيتها ما بقي وقال سفيان مرة إن شئت أعتقتها ويكون الولاء لنا فلما جاء رسول الله صلى الله عليه وسلم ذكرته ذلك فقال النبي صلى الله عليه وسلم ابتاعيها فأعتقيها فإن الولاء لمن أعتق ثم قام رسول الله صلى الله عليه وسلم على المنبر وقال سفيان مرة فصعد رسول الله صلى الله عليه وسلم على المنبر فقال ما بال أقوام يشترطون شروطا ليس في كتاب الله من اشترط شرطا ليس في كتاب الله فليس له وإن اشترط مائة مرة}

`A'ishah (may Allah be pleased with her) narrated: Barira came to seek my help regarding her manumission. I told her, “If you like I would pay your price to your masters but your Al Wala’ would be for me.” Her masters said, “If you like, you can pay what remains (of the price of her manumission), (Sufyan the sub-narrator once said), or if you like you can manumit her, but her (inheritance) Al Wala’ would be for us. “When Allah’s Messenger (peace be upon him) came, I spoke to him about it. He said, “Buy her and manumit her. No doubt Al Wala’ is for the manumitter.” Then Allah’s Messenger (peace be upon him) stood on the pulpit (or Allah’s Messenger (peace be upon him) ascended the pulpit as Sufyan once said), and said, “What about some people who impose conditions which are not present in Allah’s Book (Laws)? Whoever imposes conditions which are not in Allah’s Book (Laws), his conditions will be invalid even if he imposed them a hundred times."