Urwah reported on the authority of Sayyidah Aisha that Sayyidah Barirah (RA) came to her to seek help in buying her freedom, for she had been unable to pay anything of the agreed amount (as a mukatab). Sayyidah Aisha said to her, “Go to your owners. If the are agreeable to my paying for your freedom on your behalf and also have the right to inherit from you, I will do so. “So, she mentioned that to her people, but they refused, saying, she pays for your freedom hoping for reward (from Allah) and lets us have the right to inherit from you then it is acceptable to us.” Sayyidah Aisha (RA) mentioned that to Allah’s Messenger (SAW) He said to her “Buy her and set her free. The right to inherit belongs to one who emancipates.” He then stood up (among the people) and said, “What is the matter with the people; they put forward conditions not found in Allah’s Book. If anyone places conditions that are not in Allah’s Book then they are invalid, even if he makes the conditions a hundred times.”
[Ahmed 24576, Bukhari 2561, Muslim 1504, Abu Dawud 3929, Ibn Majah 2521, Nisai 4664]