'Show Mercy' in the Bible

Just as surely as I have done this, so surely will I never reject the descendants of Jacob. Nor will I ever refuse to choose one of my servant David's descendants to rule over the descendants of Abraham, Isaac, and Jacob. Indeed, I will restore them and show mercy to them."

They shall hold the bow and the lance: they are cruel, and will not show mercy: their voice shall roar like the sea, and they shall ride upon horses, every one put in array, like a man to the battle, against thee, O daughter of Babylon.