δεσμοφύλαξ

And when they had laid many stripes upon them, they cast them into prison, charging the jailor to keep them safely:

And the keeper of the prison awaking out of his sleep, and seeing the prison doors open, he drew out his sword, and would have killed himself, supposing that the prisoners had been fled.

And the keeper of the prison told this saying to Paul, The magistrates have sent to let you go: now therefore depart, and go in peace.