Harry Potter and the Prisoner of Azkaban
"When one wizard saves another wizard's life, it creates a certain bond between them [...] and I'm much mistaken if Voldemort wants his servant in the debt of Harry Potter."
"I don't want a connection with Pettigrew!" said Harry. "He betrayed my parents!"
"This is magic at its deepest and most impenetrable, Harry." (22.3.44-6)
"I knew your father very well, both at Hogwarts and later, Harry," he said gently. "He would have saved Pettigrew too. I am sure of it." (22.3.48)