Hadithcore
Hadith #2117410

Ibn ’Abbas (RAA) narrated that The Messenger of Allah (ﷺ) said:

“The Diyah (Blood money) of a slave who had made an agreement to buy his freedom (Mukatib) and had been killed, is paid at the rate paid for a free man (as a Diyah) as much as he has paid of the amount agreed upon, and at the rate paid for a slave as the remainder is concerned.” Related by Ahmad, Abu Dawud and Au-Nasa’i.

وَعَنْ اِبْنِ عَبَّاسٍ ‏-رَضِيَ اَللَّهُ عَنْهُمَا‏- أَنَّ اَلنَّبِيَّ ‏- صلى الله عليه وسلم ‏-قَالَ: { يُودَى اَلْمُكَاتَبُ بِقَدْرِ مَا عَتَقَ مِنْهُ دِيَةَ اَلْحُرِّ, وَبِقَدْرِ مَا رَقَّ مِنْهُ دِيَةَ اَلْعَبْدِ } رَوَاهُ أَحْمَدُ, وَأَبُو دَاوُدَ, وَالنَّسَائِيّ ُ [1]‏ .‏

References2 variants
Sunnah.com reference
Book 15, Hadith 16
Arabic/English book reference
Book 15, Hadith 1477