This is a carefully phrased line, implying much more than its surface meaning. On the surface, of course, it means that he cannot give up the silver for anything, and even the possibility of losing it is enough to make him swerve from his desired wife. Allegorically, however, the important thing is that he is wholly committed to "unlawfulness," i.e., his actions bind him to the society of law, even if they are a revolt and a crime against it. Thus he is bound to Linda (who represents that society), not only because he desires the silver, but because he desires it as a criminal.