From: "The Naked Sun"
"I'll quote the Second Law: A robot must obeey the orders given it by human beings except where such orders would conflict with the First Law. So you see, my order whould have been ignored. 'This is nonsense. The robot lacked knowledge--'. Baley leaned forward in his chair. 'Ah! We have it. Now let's recite the First Law as it should be stated: 'A robot may do nothering which, to its knowledge, will harm a human beign; nore, through inaction, knowingly, allow a human being to come to harm.'