Read all Ahadith in the chapters on manumission (of slaves) by sunan ibn e majah

It was narrated from Jabir that: the Messenger of Allah (ﷺ) sold a Mudabbar.

It was narrated that Jabir bin 'Abdullah said: “A man among us promised freedom to a slave after his death, and he did not have any property other than him (this slave). So the Prophet (ﷺ) sold him, and Ibn (Nahham), a man from Banu 'Adi, bought him.”

It was narrated from Ibn`Umar that the Prophet (ﷺ) said: “The Mudabbar is part of the one third of the estate.”

It was narrated from Ibn`Abbas that the Messenger of Allah (ﷺ) said: “Any man whose slave won an bears him a child, she will be free after he dies.”

It was narrated that Ibn`Abbas said: “Mention was made of the mother of Ibrahim in the presence of the Messenger of Allah (ﷺ), and he said: 'Her son set her free.'”

Jabir bin `Abdullah was heard to say: “We used to sell our slave women and the mothers of our children (Umahat Awaldina) when the Prophet (ﷺ) was still living among us, and we did not see anything wrong with that.”

It was narrated from `Amr bin Shu'aib , from his father, from his grandfather that the Messenger of Allah (ﷺ) said: “Any slave who has made a contract to buy his freedom for one hundread Uqiyyah and pays it all except ten Uqiyyah; he is still a slave.” (One Uqiyyah is equal to 40 Dirham.)

It was narrated from Umm Salamah that the Prophet (ﷺ) said: “If anyone of you (women) has a Mukatab, and he has enough (wealth) to pay off (his contact of manumission), she must veil herself from him.”

It was narrated from Hisham bin 'Urwah, from his father, about 'Aishah the wife of the Prophet (ﷺ) - : that Barirah came to her when she was came to her when she was Muktabah, and her masters had written a contract of manumission for nine Uqiyyah. She (`Aishah) said: “If your masters wish I will pay them that in one sum, and the right of inheritance will belong to me.” He said: “So she went to her masters and told them about that, but they insisted that the right of inheritance should belong to them. `Aishah mentioned that to the Prophet (ﷺ) and he said: 'Do it.' Then the Prophet (ﷺ) stood up and addressed the people. He praised and glorified Allah (SWT), then he said: 'What is the matter with some people who stipulated conditions that are not in the Book of Allah (SWT)? Every conditions that is not in the Book of Allah (SWT) is invalid, even if there are one hundred conditions. The Book of Allah(SWT) is more deserving of being followed and the conditions of Allah (SWT) are more binding. And the Wala belongs to the one who manumits (the slave).”