On that account : We ordained for the Children of Israel that if any one slew a person - unless it be for murder or for spreading mischief in the land - it would be as if he slew the whole people : and if any one saved a life , it would be as if he saved the life of the whole people . Then although there came to them Our messengers with clear signs , yet , even after that , many of them continued to commit excesses in the land .