John Calvin on Acts 16:34

34. He rejoiceth that he believed. The external profession of faith was before commended in the jailer; now the inward fruit thereof is described. When he did lodge the apostles, “Hospitaliter,” hospitably. and was not afraid of punishment, but did courteously entertain them in his own house, otherwise than he was enjoined by the magistrate, he did testify that his faith was not idle. And that joy whereof Luke speaketh in this place is a singular good thing, which every man hath from his faith. There is no great torment than an evil conscience; for the unbelievers, though the seek by all means to bring themselves into a certain amazedness, yet because they have no peace with God, they must needs quake and tremble. But admit they perceive not their present torments, yea, they rage and play the madmen through mad and unbridled licentiousness; yet are they never quiet, neither do they enjoy quiet joy. “Nec sereno gaudio potiuntur,” nor do they obtain serene joy. Therefore, sincere and quiet stable joy proceedeth from faith alone, when we perceive that God is merciful to us. In this respect, Zacharias saith, “Rejoice and be glad, O daughter of Sion, behold, they King cometh.” Yea, this effect is everywhere in the Scripture attributed to faith, that it maketh the souls joyful. Therefore, let us know that faith is not a vain or dead imagination, but a lively sealing [sense] of the grace of God, which bringeth perfect joy by reason of the certainty of salvation, whereof it is meet that the wicked be void, who do both fly from the God of peace, and disturb all righteousness.

Acts 16:35-40

35. And when it was day, the magistrates sent the apparitors, [officers,] saying, Let those men go. 36. And the keeper of the prison told these words to Paul, The magistrates have sent to loose you: now therefore going out, depart in peace. 37. And Paul said to them, After that they have beaten us openly, before our cause was known, seeing that we be Romans, they have cast us into prison; and now they cast us out privily? No, surely; but let them come themselves and fetch us out. 38. And the apparitors [officers] told these words to the magistrates; who feared, after that they heard that they were Romans. 39. And they came and besought them; and when they had brought them out, they requested that they would depart out of the city. 40. And coming out of the prison, they entered in unto Lydia; and when they had seen the brethren, they comforted them, and departed.