hair's-breadth

But if I knew my Purpose I belike would not swerve a hairs-breadth from my own course which is an unhallowedly selfish one.

He jumped madly to avoid it, and it missed him only by a hairs breadth.

The champagne bottle whizzed past his head, missing him by a hairs-breadth and smashing on the opposite wall.

He accomplished two daring things—the one successfully, while the other was within a hairs-breadth of a very shocking issue.

Ah, you may laugh, it was a miraculous escape, he was within a hairs breadth of the noose; but I saved his neck for him.