What is the significance of keeping Sams hair in the bible from the Pact

Sam's mother put his hair inside of the Bible after his first haircut, something she gave into only because the administrators at his school informed her that students and teachers were mistaking him for a girl. When she put his hair in the Bible, she told him "I'm keeping you in here." Sam likened the many times he found himself in tight situations to what she'd said. He felt that there was a significant reason that when he found himself in a situation he couldn't get out of— another door would open— and he'd find his way. He believed it had everything to do with faith.