a Mukatab was killed at the time of the Messenger of Allah and he commanded that the Diyah be paid (equivalent) to the Diyah for a free man, (proportionate to the amount he had paid off towards buying his freedom).
أَنَّ مُكَاتَبًا قُتِلَ عَلَى عَهْدِ رَسُولِ اللَّهِ ﷺ فَأَمَرَ أَنْ يُودَى مَا أَدَّى دِيَةَ الْحُرِّ وَمَا لاَ دِيَةَ الْمَمْلُوكِ