The Mukatab
Malik :: Book 39 : Hadith 39.2.4
Malik said, "The generally agreed on way of doing things among us is that when slaves write their kitaba together in one kitaba, and some are responsible for others, and they are not reduced anything by the death of one of the responsible ones, and then one of them says, 'I can't do it,' and gives up, his companions can use him in whatever work he can do and they help each other with that in their kitaba until they are freed, if they are freed, or remain slaves if they remain slaves."
Malik said, "The generally agreed on way of doing things among us is that when a master gives a slave his kitaba, it is not permitted for the master to let anyone assume the responsibility for the kitaba of his slave if the slave dies or is incapable. This is not part of the sunna of the muslims. That is because when a man assumes responsibility to the master of a mukatab for what the mukatab owes of his kitaba, and then the master of the mukatab pursues that from the one who assumes the responsibility, he takes his money falsely. It is not as if he is buying the mukatab, so that what he gives is part of the price of something that is his, and neither is the mukatab being freed so that the price established for him buys his inviolability as a free man. If the mukatab is unable to meet the payments he reverts to his master and is his slave. That is because kitaba is not a fixed debt which can be assumed by the master of the mukatab. It is something which, when it is paid by the mukatab, sets him free. If the mukatab dies and has a debt, his master is not one of the creditors for what remains unpaid of the kitaba. The creditors have precedence over the master. If the mukatab cannot meet the payments, and he owes debts to people, he reverts to being a slave owned by his master and the debts to the people are the liability of the mukatab. The creditors do not enter with the master into any share of the price of his person."
Malik said, "When people are written together in one kitaba and there is no kinship between them by which they inherit from each other, and some of them are responsible for others, then none of them are freed before the others until all the kitaba has been paid. If one of them dies and leaves property and it is more than all of what is against them, it pays all that is against them . The excess of the property goes to the master, and none of those who have been written in the kitaba with the deceased have any of the excess. The master's claims are overshadowed by their claims for the portions which remain against them of the kitaba which can be fulfilled from the property of the deceased, because the deceased had assumed their responsibility and they must use his property to pay for their freedom. If the deceased mukatab has a free child not born in kitaba and who was not written in the kitaba, it does not inherit from him because the mukatab was not freed until he died."