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). (Using translation from Nasāʾī 4812)
أَنَّ مُكَاتَبًا قُتِلَ عَلَى عَهْدِ النَّبِيِّ ﷺ وَقَدْ أَدَّى طَائِفَةً «فَأَمَرَ أَنْ يُودَى مَا أَدَّى مِنْهُ دِيَةَ الْحُرِّ وَمَالًا دِيَةَ الْمَمْلُوكِ»