It is narrated from Yahya bin Saeed that Marwan bin Hakam wrote to Muawiyah bin Abi Sufyan that a madman has been brought to me who has killed a person. Muawiyah wrote in reply that imprison him and do not take retribution from him, because retribution is not applicable to a madman.

Imam Malik, may Allah have mercy on him, said that if an adult and a minor together intentionally kill a person, then retribution (qisas) will be taken from the adult, and half of the blood money (diyah) will be obligatory upon the minor.

Imam Malik, may Allah have mercy on him, said that similarly, if a free person and a slave together intentionally kill a slave, then the slave will be killed in retribution, and the free person will be liable for half the value of that slave.