Disqualified by reason of death or insanity of adverse party

Section 23. — Parties or assignor of parties to a case, or persons in whose behalf a case is prosecuted, against an executor or administrator or other representative of a deceased person, or against a person of unsound mind, upon a claim or demand against the estate of such deceased person or against such person of unsound mind, cannot testify as to any matter of fact occurring before the death of such deceased person or before such person became of unsound mind. (Rule 130)