The reason not to oppress the poor is not just moral principle — it is because God is their advocate and defender. He will 'plead their cause' in the highest court. And He will do to their oppressors what they did to the poor — spoil the soul of those who spoiled them. This is God's justice: precise and inevitable.
Memory phrase: God defends the poor.
Talk about it: Why can poor people trust that they are not alone?
Prayer: God, thank You for defending those who have no one else.