Sayyiduna Abdullah bin Abbas (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) said: "A slave is not to be given anything from the spoils of war, but he may be given from the leftover household goods, and his granting of protection is valid."
Umar bin Hafs al-Makki is da'if (weak).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16815