innocent as a lamb

*innocent as a lamb

 and *innocent as a newborn babe 
1. guiltless. (*Also: as ~.) "Hey! You can't throw me in jail," cried the robber. "I'm innocent as a lamb."
2. naive; inexperienced. (*Also: as ~.) She's eighteen years old, but innocent as a newborn babe.
See also: innocent, lamb
References in classic literature ?
Some people who took the trouble to busy themselves in the matter said that she was the criminal, whilst others vowed that she was as innocent as a lamb and that her odious husband was in fault.