In Don't Blame the Mud by Marty Machowski, Max is walking home from school when he decides to take a detour by the river, even though his mom told him to be careful to keep his school clothes clean. But Max doesn't stay clean for long, and when he hears his mom yelling for him to come home, he runs home and tries to hide his dirty clothes. When Max gets caught, he blames it on the mud, but even after he scrubs all the mud off of him, he still feels dirty. His parents sit Max down and explain that the mud he feels on his heart, is his guilt---his sin---and that only God can wash away the mud in his heart. Includes a section in the back to help parents engage in conversation with their children.
