Hadith 1278B1

. قَالَ مَالِك : وَذَلِكَ أَحْسَنُ مَا سَمِعْتُ فِي الرِّقَابِ الْوَاجِبَةِ، أَنَّهُ لَا يَشْتَرِيهَا الَّذِي يُعْتِقُهَا فِيمَا وَجَبَ عَلَيْهِ بِشَرْطٍ عَلَى أَنْ يُعْتِقَهَا، لِأَنَّهُ إِذَا فَعَلَ ذَلِكَ فَلَيْسَتْ بِرَقَبَةٍ تَامَّةٍ، لِأَنَّهُ يَضَعُ مِنْ ثَمَنِهَا لِلَّذِي يَشْتَرِطُ مِنْ عِتْقِهَا .
Imam Malik, may Allah have mercy on him, said that if a person is obliged to free a slave, he should not buy the slave with the condition that he will set him free, because if he buys with this condition, the seller will give a concession and reduce the price, and in this case, it will not be a complete freeing (of the slave).
Hadith Reference موطا امام مالك رواية يحييٰ / كتاب العتق والولاء / 1278B1
Hadith Takhrij «فواد عبدالباقي نمبر: 38 - كِتَابُ الْعِتْقِ وَالْوَلَاءِ-ح: 12»