Beside a measure of economic justice and the creation of a strong idea of community, the Prophet Muhammad effected a general reform of Arab society, in particular protecting its weaker segments—the poor, the orphans, the women, and the slaves. Slavery was not legally abolished, but emancipation of slaves was religiously encouraged as an act of merit TheMuslimPath - Blog.

Slaves were given legal rights, including the right of acquiring their freedom in return for payment, in installments, of a sum agreed upon by the slave and his master out of his earnings. A slave woman who bore a child by her master became automatically free after her master’s death. The infanticide of girls that was practiced among certain tribes in pre-Islamic Arabia—out of fear of poverty or a sense of shame—was forbidden.

Distinction and privileges based on tribal rank or race were repudiated in the Qurʾān and in the celebrated “Farewell Pilgrimage Address” of the Prophet shortly before his death. All are therein declared to be “equal children of Adam,” and the only distinction recognized in the sight of God is to be based on piety and good acts.

The age-old Arab institution of intertribal revenge (called thaʾr)—whereby it was not necessarily the killer who was executed but a person equal in rank to the slain person—was abolished. The pre-Islamic ethical ideal of manliness was modified and replaced by a more humane ideal of moral virtue and piety.