The phrase, "by the skin of one's teeth," which means "with
the smallest possible margin comes from the Bible. In the
Book of Job (19:20), while complaining about his pitiable
situation, Job makes a statement that the King James Bible
translates as: "My bone cleaveth to my skin and to my
flesh, and I am escaped with the skin of my teeth."

While we don't have skin on our teeth, Job's vividly
poignant phrase, like so many others from the Bible, stuck.
So now, whenever anyone narrowly escapes, they're said to
have made it "by the skin of their teeth."