'My reins' refers to the deepest inner being — the seat of emotion and thought. When a child speaks what is right, the parent's joy is not surface-level but goes to the deepest place. True speech produces deep joy in those who love us.
Memory phrase: Speak what is right and true.
Talk about it: What are some right and true things you can say that would make someone you love very happy?
Prayer: God, help my words be right and bring joy.