Sayyiduna Ibn Umar (may Allah be pleased with them both) says that the Prophet (peace and blessings be upon him) said to Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him): "O Ibn Mas'ud, do you know what Allah's ruling is concerning anyone in this Ummah who rebels?" He said: Allah and His Messenger (peace and blessings be upon him) know best. He (peace and blessings be upon him) said: "Their fleeing ones are not to be pursued, the captive is not to be killed, and the wounded is not to be hastened to his death either."
Only Kawthar bin Hakim narrated it, and he is da'if (weak).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16755