Thomas Aquinas

Second, divine mercy, in relation to divine piety as to reason, is considered. For, though he cause grief, he will have compassion according "to the abundance of his steadfast love," because, it from such a portion of divine piety (of God the Father) that one punishes in order to correct, then one comforts. For, the Book of Tobit 4:21 states: "Do not be afraid, my son, because we have become poor. You have great wealth, if you fear God and refrain from every sin and do what is pleasing in his sight."

Commentary on Lamentations ↗