Sharia recognizes the basic inequality between master and slave, between free women and slave women, between Believers and non-Believers, as well as their unequal rights. Sharia authorized the institution of slavery, using the words "abd" (slave) and the phrase "ma malakat aymanukum" ("that which your right hand owns") to refer to women slaves, seized as captives of war. Under Islamic law, Muslim men could have sexual relations with female captives and slaves. Slave women under sharia did not have a right to own property or to move freely. Sharia, in Islam's history, provided a religious foundation for enslaving non-Muslim women (and men), but allowed for the manumission of slaves. However, manumission required that the non-Muslim slave first convert to Islam. A slave woman who bore a child to her Muslim master ("umm al-walad") could not be sold, becoming legally free upon her master's death, and the child was considered free and a legitimate heir of the father.