Amr bin Shu'ayb narrates from his father, and he from his grandfather, that Abu Bakr and Umar (may Allah be pleased with them both) did not kill a free man in return for a slave.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15936
Amr bin Shu'ayb narrates from his father, and he from his grandfather, that Sayyiduna Abu Bakr and Sayyiduna Umar (may Allah be pleased with them both) did not kill a free man in return for a slave.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15937
Amir said that Sayyiduna Ali (may Allah be pleased with him) said: "It is from the Sunnah that a free man is not killed in return for a slave." [Da'if]
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15938
Ibn Abbas (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) said: "A free man is not to be killed for a slave."
There is weakness in this chain.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15939
Ali and Abdullah bin Mas'ud (may Allah be pleased with them both) said, regarding a free man who kills a slave: "Retaliation (qisas)."
This is munqati' (a broken chain).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15940
Ali and Ibn Abbas (may Allah be pleased with them both) said: "When a free man deliberately kills a slave, it is (a case of) retaliation."
Ali bin Umar (al-Daraqutni) said: No proof is established by it, because it is mursal.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15941
Bukayr (may Allah have mercy on him) said that the Sunnah is: "A free Muslim will not be killed for a slave, even if he kills him deliberately. Blood money, however, will be taken."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15943
Ibn Shihab (may Allah have mercy on him) said: There is no retaliation between a free man and a slave in anything, except that if a slave deliberately kills a free man, the slave will be killed. Imam Malik (may Allah have mercy on him) also told me the same, and Ibn Jurayj (may Allah have mercy on him) narrated the same to us from Ata (may Allah have mercy on him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15944