Maimonides’ Code

“If one person is able to save another and does not save him, he transgresses the commandment, ‘Neither shall you stand idly by the blood of your neighbor.’ (Leviticus 19:16) Similarly, if one person sees another drowning in the sea, or being attacked by bandits, or being attacked by wild animals, and, although able to rescue him either alone or by hiring others, does not rescue him; or if one hears heathens or informers plotting evil against another or laying a trap for him and does not call it to the other’s attention and let him know; or if one knows that a heathen or violent person is going to attack another and although able to appease him on behalf of the other and make him change his mind, he does not do so; or if one acts in any similar way — he transgresses in each case the injunction “Neither shall you stand idly by the blood of your neighbor.” –Maimonides’ Code, “Laws Concerning Murder and the Preservation of Life,” Chapter 1, Sections 14 and 16