Sahih al-Bukhari 7186
Narrated Jabir:
The Prophet (ﷺ) came to know that one of his companions had given the promise of freeing his slave after 
his death, but as he had no other property than that slave, the Prophet (ﷺ) sold that slave for 800 dirhams 
and sent the price to him.
حَدَّثَنَا ابْنُ نُمَيْرٍ، حَدَّثَنَا مُحَمَّدُ بْنُ بِشْرٍ، حَدَّثَنَا إِسْمَاعِيلُ، حَدَّثَنَا سَلَمَةُ بْنُ كُهَيْلٍ، عَنْ عَطَاءٍ، عَنْ جَابِرٍ، قَالَ بَلَغَ النَّبِيَّ صلى الله عليه وسلم أَنَّ رَجُلاً مِنْ أَصْحَابِهِ أَعْتَقَ غُلاَمًا عَنْ دُبُرٍ، لَمْ يَكُنْ لَهُ مَالٌ غَيْرَهُ، فَبَاعَهُ بِثَمَانِمِائَةِ دِرْهَمٍ، ثُمَّ أَرْسَلَ بِثَمَنِهِ إِلَيْهِ‏.‏