And at midnight Paul and Silas prayed, and sang praises unto God: and the prisoners heard them.

And at midnight, Paul and Silas praying, praised God. And they that were in prison, heard them.

And at midnight Paul and Silas, in praying, were praising God with singing, and the prisoners listened to them.

And at midnight Paul and Silas praying, were singing hymns to God, and the prisoners were hearing them,

But about the middle of the night, Paul and Silas were making prayers and songs to God in the hearing of the prisoners;

Then, in the middle of the night, Paul and Silas were praying and praising God. And those who were also in custody were listening to them.

And at midnight - Probably their painful posture, and the sufferings of their recent scourging, prevented their. sleeping. Yet, though they had no repose, they had a quiet conscience, and the supports of religion.
Prayed - Though they had suffered much, yet they had reason to apprehend more. They sought, therefore, the sustaining grace of God.
And sang praises - Compare the notes on Job 35:10. Nothing but religion would have enabled them to do this. They had endured much, but they had cause still for gratitude. The Christian may find more true joy in a prison than the monarch on his throne.
And the prisoners heard them - And doubtless with astonishment. Prayer and praise are not common in a prison. The song of rejoicing and the language of praise is not usual among men lying bound in a dungeon. From this narrative we may learn:
(1) That the Christian has the sources of his happiness within him. External circumstances cannot destroy his peace and joy. In a dungeon he may find as real happiness as on a throne. On the cold earth, beaten and bruised, he may be as truly happy as on a bed of down.
(2) the enemies of Christians cannot destroy their peace. They may incarcerate the body, but they cannot bind the spirit, They may exclude from earthly comforts, but they cannot shut them out from the presence and sustaining grace of God.
(3) we see the value of a good conscience. Nothing else can give peace; and amidst the wakeful hours of the night, whether in a dungeon or on a bed of sickness, it is of more value than all the wealth of the world.
(4) we see the inestimable worth of the religion of Christ. It fits for all scenes; supports in all trials; upholds by day or by night; inspires the soul with confidence in God; and puts into the lips the songs of praise and thanksgiving.
(5) we have here a sublime and holy scene which sin and infidelity could never furnish. What more sublime spectacle has the earth witnessed than that of scourged and incarcerated men, suffering from unjust and cruel inflictions, and anticipating still greater sorrows; yet, with a calm mind, a pure conscience, a holy joy, pouring forth their desires and praises at midnight, into the ear of the God who always hears prayer! The darkness, the stillness, the loneliness, all gave sublimity to the scene, and teach us how invaluable is the privilege of access to the throne of mercy in this suffering world.

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.

(15) And at midnight Paul and Silas prayed, and sang praises unto God: and the prisoners heard them.
(15) The prayers of the godly do shake both heaven and earth.

And at midnight Paul and Silas prayed, When others were asleep, and all things were still and quiet; See Gill on Psalm 119:62, and they prayed doubtless for themselves, for their deliverance in God's time and way, and for support under their present afflictions; and for supplies of grace, to enable them to bear with patience and cheerfulness, until an issue was put to them; and for their enemies, and, particularly it may be for the jailer, who had used them so ill; and for the churches of Christ, for all the saints, and for the spread and success of the Gospel:
and sang praises unto God; or "sang an hymn to God", very likely one of David's psalms, or hymns: for the book of Psalm is a book, of hymns, and several of the psalms are particularly called hymns; this showed not only that they were cheerful, notwithstanding the stripes that were laid upon them, and though their feet were made fast in the stocks, and they were in the innermost prison, in a most loathsome and uncomfortable condition; and though they might be in expectation of greater punishment, and of death itself; but also that they were thankful and glorified God, who had counted them worthy to suffer for his name's sake:
and the prisoners heard them; for it seems there were other prisoners besides them, and who were in the outer prison: and from hence it appears, that their prayer was not merely mental; nor was their singing praises only a making melody in their hearts, but were both vocal; and it might be chiefly for the sake of the prisoners, that they both prayed and praised in this manner, that they might hear and be converted; or at least be convicted of the goodness of the cause, for which the apostles suffered.

The consolations of God to his suffering servants are neither few nor small. How much more happy are true Christians than their prosperous enemies! As in the dark, so out of the depths, we may cry unto God. No place, no time is amiss for prayer, if the heart be lifted up to God. No trouble, however grievous, should hinder us from praise. Christianity proves itself to be of God, in that it obliges us to be just to our own lives. Paul cried aloud to make the jailer hear, and to make him heed, saying, Do thyself no harm. All the cautions of the word of God against sin, and all appearances of it, and approaches to it, have this tendency. Man, woman, do not ruin thyself; hurt not thyself, and then none else can hurt thee; do not sin, for nothing but that can hurt thee. Even as to the body, we are cautioned against the sins which do harm to that. Converting grace changes people's language of and to good people and good ministers. How serious the jailer's inquiry! His salvation becomes his great concern; that lies nearest his heart, which before was furthest from his thoughts. It is his own precious soul that he is concerned about. Those who are thoroughly convinced of sin, and truly concerned about their salvation, will give themselves up to Christ. Here is the sum of the whole gospel, the covenant of grace in a few words; Believe in the Lord Jesus Christ, and thou shalt be saved, and thy house. The Lord so blessed the word, that the jailer was at once softened and humbled. He treated them with kindness and compassion, and, professing faith in Christ, was baptized in that name, with his family. The Spirit of grace worked such a strong faith in them, as did away further doubt; and Paul and Silas knew by the Spirit, that a work of God was wrought in them. When sinners are thus converted, they will love and honour those whom they before despised and hated, and will seek to lessen the suffering they before desired to increase. When the fruits of faith begin to appear, terrors will be followed by confidence and joy in God.

And at midnight Paul and Silas prayed and sang praises--literally, "praying, were singing praises"; that is, while engaged in pouring out their hearts in prayer, had broken forth into singing, and were hymning loud their joy. As the word here employed is that used to denote the Paschal hymn sung by our Lord and His disciples after their last Passover (Matthew 26:30), and which we know to have consisted of Psalm. 113:1-118:29, which was chanted at that festival, it is probable that it was portions of the Psalm, so rich in such matter, which our joyous sufferers chanted forth; nor could any be more seasonable and inspiring to them than those very six Psalm, which every devout Jew would no doubt know by heart. "He giveth songs in the night" (Job 35:10). Though their bodies were still bleeding and tortured in the stocks, their spirits, under "the expulsive power of a new affection," rose above suffering, and made the prison wails resound with their song. "In these midnight hymns, by the imprisoned witnesses for Jesus Christ, the whole might of Roman injustice and violence against the Church is not only set at naught, but converted into a foil to set forth more completely the majesty and spiritual power of the Church, which as yet the world knew nothing of. And if the sufferings of these two witnesses of Christ are the beginning and the type of numberless martyrdoms which were to flow upon the Church from the same source, in like manner the unparalleled triumph of the Spirit over suffering was the beginning and the pledge of a spiritual power which we afterwards see shining forth so triumphantly and irresistibly in the many martyrs of Christ who were given up as a prey to the same imperial might of Rome" [NEANDER in BAUMGARTEN].
and the prisoners heard them--literally, "were listening to them," that is, when the astounding events immediately to be related took place; not asleep, but wide awake and rapt (no doubt) in wonder at what they heard.

Prayed, and sang praises. Never before had such sounds at midnight been heard from that inner dungeon. Bound, fettered, tortured, the spirit still had liberty, could pray, and praise God. God heard them, too, for there was a great earthquake. See Acts 4:31. It was God's angel to loose their bonds, open the prison doors, and magnify their work.
The keeper . . . drew out his sword. He was responsible with his life for the safety of his prisoners. Fancying them gone, he determined, like a Roman, to anticipate disgrace by death. Right there at Philippi, Brutus and Cassius had each inflicted self-death. Self-murder was very common among the Romans.
We are all here. Paul and Silas had no inclination of escape; the other prisoners were probably too much astounded.
Called for a light. "Lights" in the Revision. All was darkness.
Fell down before Paul and Silas. Awed, believing that they were under Divine protection.
Brought them out. Of the inner prison, probably into the prison court.
What must I do to be saved? Saved from suicide, no danger of death because the prisoners are there, awed by the wonderful events, aware that these men preached a new religion and salvation, he asks this question.
Believe on the Lord Jesus Christ. He was a heathen. Faith was the first essential step. To Jews, on the day of Pentecost, already believing Peter's proposition, he said, in answer to the same question, "Repent and be baptized;" but the heathen jailer was not ready for this. Faith must first be wrought, and then that faith, leading to the acceptance of Christ, would save. His faith would save, because it would be the power that would lead him to follow Christ.
And thy house. We learn from the next verse that "his house" could listen the word of the Lord, hence were not infants. It was needful to preach the word, for this heathen knew almost nothing of the gospel. In preaching it, Paul preached baptism, for that follows in Acts 16:33.
Washed their stripes. They were all covered with bruises, blood and dust. His heart is now changed and filled with the spirit of mercy. Howson suggests that they were washed in the tank or reservoir within the prison court, supplied by the water from the roof. Here also all were baptized straightway. On the baptism of his household, see notes on Acts 16:15 above.
Brought them into his house. The Revision says "up;" that is, from the court below where he washed their stripes, and was baptized. They were "brought out" (Acts 16:30), the word was preached "in his house" (Acts 16:32), they were then "taken" to the place of baptism (Acts 16:33), after he "brought them into his house" (Acts 16:34).
Believing in God with all his house. All his household were, therefore, believers.

Paul and Silas sung a hymn to God - Notwithstanding weariness, hunger stripes, and blood. And the prisoners heard - A song to which they were not accustomed.