what specific language in the document indicates that the freedom of slaves is for moral reasons? (The Emancipation Proclamation)

The Proclamation announced the acceptance of black men into the Union Army and Navy, enabling the liberated to become liberators

One of the main reasons why the Emancipation Proclamation is considered a moral document is because of the reasoning it employs to justify the end of slavery. The Emancipation Proclamation states that slaves deserve their freedom simply because they are human beings and all humans have the right to be free. This is an argument that now forms the basis of doctrines such as that of universal human rights.