Axioms of Hilbert Proof System Instance 1 for Predicate Logic are Tautologies

Theorem
Let $\mathscr H$ be Instance 1 of a Hilbert proof system for predicate logic.

Then the axioms of $\mathscr H$ are tautologies.

Axiom 1
This is precisely the statement of Propositional Tautology is Tautology in Predicate Logic.