Acts 16:24-28

He, having received such a [strict] command, threw them into the inner prison (dungeon) and fastened their feet in the stocks [in an agonizing position]. But about midnight when Paul and Silas were praying and singing hymns of praise to God, and the prisoners were listening to them; suddenly there was a great earthquake, so [powerful] that the very foundations of the prison were shaken and at once all the doors were opened and everyone’s chains were unfastened. When the jailer, shaken out of sleep, saw the prison doors open, he drew his sword and was about to kill himself, thinking that the prisoners had escaped. But Paul shouted, saying, “Do not hurt yourself, we are all here!”