Acts 16:34

‘And he brought them up into his house, and set food before them, and rejoiced greatly, with all his house, having believed in God.'

Furthermore he also brought them into the part of the prison building which was his home, and set food before them. And he and all his house were rejoicing greatly (a sign of the working of the Holy Spirit. This work was genuine) because they had believed in God.

We see here that the jailer was already a new creation (2 Corinthians 5:17). Never before had he bathed prisoners wounds, fed them at his table, and rejoiced greatly in God. He was a new man. And many a prisoner in the future would have cause to rejoice in it. As another has said, ‘I care not a jot for that man's religion whose very dog and cat are not the better for it'. His prison would never treat people in the same way again.