swear on a stack of Bibles—promise solemnly that what one says is true:
- Your telephone company will swear on a stack of Bibles that nothing will disrupt service to you, the valued customer.
swear on the Bible—
1. place one’s hand on the Bible in a court of law pledging to tell the truth:
- A court officer will ask you to swear on the Bible or promise to tell the truth.
2. = swear on a stack of Bibles:
- There are probably a lot of people that think I’m lying, and I swear on the Bible that this story is true.