‘Imrān ibn Husayn reported: The Prophet (may Allah's peace and blessings be upon him) obtained the freedom of two Muslim men in captivity in exchange for a man from the polytheists.
In this Hadīth, ‘Imrān ibn Husayn (may Allah be pleased with him) says that the Prophet (may Allah's peace and blessings be upon him) gave the polytheists a man from them and took two Muslim men from them instead. The Muslim jurists say that if the Muslims take prisoners of war, the Imām has four choices regarding them. These choices should be based upon the ruler's keenness to realize the best interest of Muslims. They are: killing them, enslaving them, setting them free for nothing, or setting them free for money or in exchange for Muslims imprisoned by the disbelievers.