Bors felt as if he'd been hit over the head. This was ridiculous! He'd planned and carried out the destruction of that warship because the information of its existence and location was verified by a magnetometer.

But, if he'd known how the information had been obtained--if he'd known it had been guessed at by a discharged spaceport employee, and a paranoid personality, and a man who used a hazel twig or something similar--if he'd known that, he'd never have dreamed of accepting it. He'd have dismissed it flatly! (Summary from the Gutenberg text)