491. Whoever, being bound by a lawful contract to attend on or to supply the wants of any person who by reason of youth, or of unsoundness of mind, or of a disease or bodily weakness, is helpless or incapable of providing for his own safety or of supplying his own wants, voluntarily omits so to do, shall be punished with imprisonment for a term which may extend to three months or with fine which may extend to four hundred ringgit or with both.