Why does jean valjean tell cosette that they must forgive the thenariders?

Jean Valjean tells Cosette that they must forgive the Tenardiers because he believes in the power of forgiveness and compassion. He wants to teach Cosette that holding onto anger and resentment only perpetuates negativity, and that forgiveness can lead to inner peace and healing. Valjean also understands that carrying hatred only brings suffering to oneself, and he wants Cosette to embody love and understanding.