Bulugh al-Maram, Book 15, Hadith 1433 (In-Book)

Ibn ’Abbas (RAA) narrated that The Messenger of Allah 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.‏ ‏1 ‏- صحيح.‏ رواه أحمد (1 / 222‏- 223 و 226 و 260)‏، وأبو داود (4581)‏، والنسائي (8 / 46)‏ واللفظ لأحمد.‏

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also referenced under: Book 15, Hadith 1477 (English)