Narrated ‘A'isha said Barira came telling her she had arranged to buy her freedom for nine uqiyas; one to be paid annually, and asking her to help her. ‘A’isha replied, “If your people are willing that I should count them out to them all at one time and set you free, I shall do so, and I shall have the right:
What is the matter with people who make conditions which are not in God’s Book? Any condition which is not in God’s Book is worthless. Even if there are a hundred conditions, God’s decision is more valid and God's condition is more binding. The right of inheritance belongs only to the one who has set a person free.”
I bought a slave and made him earn something for me, but afterwards I found a defect in him and so brought a case regarding him before ‘Umar b. ‘Abd al-‘Aziz, who decided in my favour that I should return him, but against me that I should return what he had earned. I therefore went to ‘Urwa and informed him, and he replied that he would go that evening to him and tell him he had been informed by ‘A'isha that God’s Messenger had given judgment in a similar case that any profit goes to the one who bears responsibility*. ‘Urwa went to him, and he gave judgment in my favour that I should receive the profit from the one for whom he had given the decision against me.
* al-Kharaj bid daman. After a sale any profit which accrues belongs to the buyer.
I was travelling on a camel of mine which had grown jaded when the Prophet passed by and struck it, with the result that it went as it had never done before. He then said, “Sell it to me for a wuqiya*”. I agreed, but made the stipulation that I should be allowed to ride it home. Then when I came to Medina I took the camel to him and he paid me its price in ready money. In a version he said, “He gave me its price and returned it to me." In a version by Bukhari he said to Bilal, “Pay him and give something extra," so he gave the money adding a qirat (A small coin, probably meaning here a sixteenth of a dirham).
(Bukhari and Muslim.)
*This and the more common form uqiya used below in the tradition from 'A'isha is an amount equivalent to forty dirhams.