Urwah narrated that :
'Aishah had informed him that Barrirah came to her ('Aishah) seeking her help for her writ of emancipation, and she had not yet paid anything for her writ of emancipation. So 'Aishah said to her: 'Return to your people, and if they agree to me paying for your writ of emancipation and that your Wala will be for me, then I will do so. So Barrirah mentioned that to her people and they refused. They said: If she wants the reward for (freeing) you while the Wala is for us, then let her do it. So I mentioned that to the Messenger of Allah (S.A.W) and the Messenger of Allah (S.A.W) said: Buy her, then free her, for the Wala is only for the one who frees. Then the Messenger of Allah (S.A.W) stood and said: What is the case of people who make conditions that are not in Allah's Book? Whoever makes a condition that is not in Allah's Book, then it will not be so for him, even if he were to make a condition a hundred times.