acts 12:6 And when Herod would have brought him forth, the same night Peter was sleeping between two soldiers, bound with two chains: and the keepers before the door kept the prison. - Free Bible Online

      6. And when Herod would have brought him forth--"was going to bring him forth."
      the same night--but a few hours before the intended execution. Thus long were the disciples kept waiting; their prayers apparently unavailing, and their faith, as would seem from the sequel, waxing feeble. Such, however, is the "law" of God's procedure (De 32:36 and see on Joh 21:3).
      Peter was sleeping between two soldiers, bound with two chains--Roman prisoners had a chain fastened at one end to the wrist of their fight hand, and at the other to the wrist of a soldier's left hand, leaving the right arm of the keeper free in case of any attempt to escape. For greater security the prisoner was sometimes, as here, chained to two soldiers, one on each side. (See Ac 21:23.) Ye think your prey secure, bloodthirsty priests and thou obsequious tyrant who, to "please the Jews," hast shut in this most eminent of the servants of Christ within double gates, guarded by double sentinels, while double keepers and double chains seem to defy all rescue! So thought the chief priests, who "made the sepulchre of the Lord sure, sealing the stone and setting a watch." But "He that sitteth in heaven shall laugh at you." Meanwhile, "Peter is sleeping!" In a few hours he expects a stingless death; "neither counts he his life dear unto him, so that he may finish his course with joy and the ministry which he has received of the Lord Jesus." In this frame of spirit he has dropped asleep, and lies the picture of peace.

JFB.