Imam al-Sha'bi (may Allah have mercy on him) narrates from Judge Shurayh (may Allah have mercy on him) that he said: Sayyiduna Umar (may Allah be pleased with him) wrote to me: "Do not make anyone an heir of a captive without proof."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18337