1 Corinthians 14:21-22

In the Law it is written, “BY MEN OF STRANGE TONGUES AND BY THE LIPS OF STRANGERS I WILL SPEAK TO THIS PEOPLE, AND EVEN SO THEY WILL NOT LISTEN TO ME,” says the Lord. So then tongues are for a sign, not to those who believe but to unbelievers; but prophecy is for a sign, not to unbelievers but to those who believe.