The Prophet (peace and blessings be upon him) said: "If people were given (what they ask) merely on the basis of their claims, some people would claim the blood and the wealth of others; but the oath is upon the one against whom the claim is made."
Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said that Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) would not make anyone an heir of a captive (hamil). (That is, a captive who is moved from place to place.)
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18335