This song is the cry of a soul afflicted by the evil actions of others. It is a sad but true fact of life that this sort of thing is a daily reality. People sin against us. They can be cruel, heartless and completely evil to us. But we have a resource and refuge. We can cry out to God.
When people are bad to us, God is still good. He can deliver us. He can free us. He can cut the cords even when we are being bound by the hatred of another person's actions.
The African-American church was born out of the evils of American slavery. It arose in affliction. Yet even today, worship in an African-American church is lively and free! The cords were cut by God's goodness and still show that freedom a century and a half later. God sets the captives free; God rewards the righteous because He is righteous.