حَدَّثَنَا أَحْمَدُ بْنُ مَنِيعٍ، حَدَّثَنَا إِسْمَاعِيلُ بْنُ إِبْرَاهِيمَ، عَنْ أَيُّوبَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏"‏ مَنْ أَعْتَقَ نَصِيبًا - أَوْ قَالَ شِقْصًا أَوْ قَالَ شِرْكًا لَهُ فِي عَبْدٍ فَكَانَ لَهُ مِنَ الْمَالِ مَا يَبْلُغُ ثَمَنَهُ بِقِيمَةِ الْعَدْلِ فَهُوَ عَتِيقٌ وَإِلاَّ فَقَدْ عَتَقَ مِنْهُ مَا عَتَقَ ‏"‏ ‏.‏ قَالَ أَيُّوبُ وَرُبَّمَا قَالَ نَافِعٌ فِي هَذَا الْحَدِيثِ يَعْنِي فَقَدْ عَتَقَ مِنْهُ مَا عَتَقَ ‏.‏ قَالَ أَبُو عِيسَى حَدِيثُ ابْنِ عُمَرَ حَدِيثٌ حَسَنٌ صَحِيحٌ وَقَدْ رَوَاهُ سَالِمٌ عَنْ أَبِيهِ عَنِ النَّبِيِّ صلى الله عليه وسلم نَحْوَهُ ‏.‏

Ibn 'Umar narrated that the Prophet (PBUH) said: "Whoever frees a portion" or, he said: "a part" or he said: "a share he owns of a slave, then he can afford the remainder of the price according to the reasonable price, then he will be free. Otherwise he has freed as much as he has freed (only)." Ayyub (one of the narrators) said: "Perhaps Nafi said in this Hadith: 'Meaning he has freed as much of him as he has freed.'" Translation Not Available

Book Ref: Jamiya Tirmidhi Book 15 Hadith 1346
Web Ref:  Jamiya Tirmidhi Vol 3 Book 13 Hadith 1346