It is error for any judge, during the progress of any case, or in his charge to the jury, to express or intimate his opinion as to what has or has not been proved. Should any judge violate this Code section, the violation shall be held by the Supreme Court or Court of Appeals to be error, the decision in the case shall be reversed, and a new trial shall be granted in the court below with such directions as the Supreme Court or the Court of Appeals may lawfully give.
OCGA § 9-10-7