Adam Clarke on Acts 16:25

At midnight Paul and Silas - sang praises - Though these holy men felt much, and had reason to fear more, yet they are undismayed, and even happy in their sufferings: they were so fully satisfied that they were right, and had done their duty, that there was no room for regret or self-reproach. At the same times they had such consolations from God as could render any circumstances not only tolerable, but delightful. They prayed, first, for grace to support them, and for pardon and salvation for their persecutors; and then, secondly, sang praises to God, who had called them to such a state of salvation, and had accounted them worthy to suffer shame for the testimony of Jesus. And, although they were in the inner prison, they sang so loud and so heartily that the prisoners heard them.