The Cow - 2:177
It is not good that you turn your faces towards the east or the west. The righteous are those who believe in Allah, the Last Day, the angels, the Book and the Prophets, and they give freely to relatives, orphans, the needy, the stranded, the beggars, and to free the slaves, and they observe the prayer, and pay the zakat, and keep their word when they contract, and they resist hardship, distress and oppression. It is they who are the righteous, and it is they who are the virtuous.
they gladly donate money to help free slaves;
The City/90:12
Do you know what the hard way is?
The City/90:13
To free the slaves;
The Repentance/9:60
Alms, as an obligation from Allah, should be given to the poor, to the needy, to those who labor, to sympathizers, for the freedom of slaves, to debtors, to the way of Allah, and to the wayfarers. Allah is All-Knowing, All-Wise.