And the Heavens Answered Amen!

Once the Rav told me about a certain Jew, who dealt in religious objects, who came to see him accompanied by a scribe who wanted to consult with the Rav about all kinds of problems he was having. After the Rav heard the problems, he told the Jew, "Go check if you have mezuzot at home!"
The Jew was shaken by the Rav’s reaction. "It’s absolutely obvious that I have mezuzot at home – I sell mezuzot and I myself put up the mezuzot in my home!"
When they left, the scribe tried to explain that the Rav intended him to check if his mezuzot were kosher. When he got home, he went to check the mezuzot, and discovered to his astonishment that the mezuzot cases were empty – no parchment inside them!
Rabbi Tweezer relates, "I asked the Rav, ‘How did the honored Rav know that the mezuzot cases were empty?’
"He replied, ‘From out of my mouth and the Heavens answered amen…’