Charles Spurgeon Commentary Acts 16:26

"and suddenly there was a great earthquake, so that the foundations of the prison-house were shaken: and immediately all the doors were opened, and every one`s bands were loosed." — Acts 16:26 (ASV)

And suddenly there was a great earthquake, so that the foundations of the prison were shaken: and immediately all the doors were opened, and every one's bands were loosed.

This was no common earthquake. An ordinary earthquake might have brought the prison down about their ears; but it would not have loosed the bands of the prisoners.

And the prisoners heard them.

Paul and Silas were in the lower prison. The sound of their prayer and praise rose up through the different tiers of cells where other prisoners were confined.