A robot may not injure a human being, or, through inaction, allow a human being to come to harm.
More from Isaac Asimov
The most hopelessly stupid man is he who is not aware that he is wise
Permalink to quote #22 A robot must obey the orders given it by human beings except where such orders would conflict with the First Law.
Permalink to quote #24 It's a poor blaster that doesn't point both ways.
Permalink to quote #21