Nehemiah 5:13

Then Ezra blessed Yahweh the great God. And all the people answered, “Amen, Amen!” while lifting up their hands; then they bowed low and worshiped Yahweh with their faces to the ground.

The word which came to Jeremiah from Yahweh after King Zedekiah had cut a covenant with all the people who were in Jerusalem to proclaim release to them:

But when they resisted and blasphemed, he shook out his garments and said to them, “Your blood be on your own heads! I am clean. From now on I will go to the Gentiles.”

Otherwise if you bless in the spirit only, how will the one who fills the place of the uninformed say the “Amen” at your giving of thanks, since he does not know what you are saying?