Is it permissible to enslave people nowadays while there are no legitimate wars?
Or was this confined to the time of the Prophet (peace be upon him), for there were legitimate wars? Please, substantiate your answer with proofs.
There is no doubt that the wars that took place between the Prophet (peace be upon him) and the disbelievers were legitimate. Some of the disbelievers were taken as slaves in these wars. There were also legitimate wars between Muslims and disbelievers during the reign of the Rightly-Guided Caliphs and those who came after them in the first three generations. They followed the Prophet's Sunnah in releasing the prisoners, accepting the ransom, taking them in slavery or killing them (Part No. 16; Page No. 573) acting upon the best interest of Muslims, as decided by the ruler in conformity with the Qur'an and the Sunnah of the Messenger of Allah (peace be upon him). All Imams agree that the ruling of slavery remains the same until now, therefore, if there are legitimate wars between Muslims and disbelievers and Muslims were victorious and captured some disbelievers, the Muslim ruler may release them, accept the ransom, kill or enslave them according to the best interest of Muslims acting upon the Qur'an and the Sunnah. If there are no legitimate wars, it is not permissible to enslave people. As for those who were enslaved in a legitimate war and continued to be in slavery by multiplication and inheritance, they will stay in this state until they gain freedom. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.