In the book Uncle Tom's Cabin what voice does Tom hear that Legree will never hear as shown in this excerpt?

In chapter 31 of the book Uncle Tom's Cabin what voice does Tom hear that Legree will never hear as shown in this excerpt? "Fear not! For I have redeemed thee. I have called thee by my name. Thou are MINE!” But Simon Legree heard no voice. That voice is one he never shall hear. He only glared for a moment on the downcast face of Tom, and walked off.