Methodists and Quakers especially worked to convince slaveholders to manumit slaves.
From the en.wikipedia.org
In 1829 Wood had refused either to manumit her or even allow her to be bought out of his control.
From the en.wikipedia.org
Muhammad would send his companions like Abu Bakr and Uthman ibn Affan to buy slaves to manumit them.
From the en.wikipedia.org
Napoleon refused to manumit the Russian serfs because of concerns this might provoke a reaction in his army's rear.
From the en.wikipedia.org
If the master does not have sufficient wealth to facilitate this, she or he must either sell, hire out, or manumit the slave as ordered.
From the en.wikipedia.org
We do hold George Washington accountable for the fact that he did not manumit his slaves during his lifetime, and that would have made him a greater statesman if he had.
From the washingtonpost.com
More examples
Free from slavery or servitude
(manumission) the formal act of freeing from slavery; "he believed in the manumission of the slaves"
Manumission is the act of a slave owner freeing his or her slaves. In the United States before the passage of the Thirteenth Amendment to the United States Constitution, which abolished slavery, this often happened on the death of the owner, as a condition of their will.
Manumission is the freeing of a slave or serf from indentured service.
(manumission) A grant of legal freedom to an individual slave. (p. 505)
(Manumission) The act by which a lord free a serf.
(Manumission) The freeing or emancipation of chattel slaves by their owners, which became more com mon in the upper South in the wake of so much talk during the American Revolution about human lib erty. ...
(Manumission) a formal written act to free slaves
(Manumission) legal process (and related documents) by which enslaved Africans could buy their freedom or be freed by their owner