Acts 16:26

“And suddenly there was a great earthquake, etc.] An extraordinary and unusual one; which did not arise from natural causes, from wind being pent up in the earth, but from the prayers and praises of the saints, going up to heaven; when God was pleased to testify his presence and power this way; and the effects which followed upon this earthquake, show it to be a supernatural one: so that the foundations of the prison were shaken; not the roof and walls only, as is common in earthquakes, but the very foundation also; and yet the edifice was not thrown down, as is usual when the foundation is shaken: and immediately all the doors were opened; both of the outer and inner prisons, which is…”

“And suddenly there was a great earthquake--in answer, doubtless, to the prayers and expectations of the sufferers that, for the truth's sake and the honor of their Lord, some interposition would take place. every one's bands--that is, the bands of all the prisoners. were loosed--not by the earthquake, of course, but by a miraculous energy accompanying it. By this and the joyous strains which they had heard from the sufferers, not to speak of the change wrought on the jailer, these prisoners could hardly fail to have their hearts in some measure opened to the truth; and this part of the narrative seems the result of information afterwards communicated by one or more of these men.”

“And suddenly - While they were praying and singing. A great earthquake - Matthew 28:2. An earthquake, in such circumstances, was regarded as a symbol of the presence of God, and as an answer to prayer. See the notes on Acts 4:31. The design of this was, doubtless, to furnish them proof of the presence and protection of God, and to provide a way for them to escape. It was one among the series of wonders by which the gospel was established, and the early Christians protected amidst their dangers. And immediately all the doors were opened - An effect that would naturally follow from the violent concussion of the earthquake. Compare Acts 5:19. Everyone’s bands were loosed - This was evidently a…”

“16:26 The massive earthquake is reminiscent of the great earthquake at Jesus’ resurrection (Matt 28:2-3).”

“suddenly: Act 4:31, Act 5:19, Act 12:7, Act 12:10; Mat 28:2; Rev 6:12, Rev 11:13 and every: Psa 79:11, Psa 102:20, Psa 146:7; Isa 42:7, Isa 61:1; Zac 9:11, Zac 9:12 Acts 16:27”