acts 16:25 And at midnight Paul and Silas prayed, and sang praises unto God: and the prisoners heard them. - Free Bible Online

      25. 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 (Mt 26:30), and which we know to have consisted of Ps 113:1-118:29, which was chanted at that festival, it is probable that it was portions of the Psalms, 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 Psalms, 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.

JFB.