Bede : And striking the side of Peter, he raised him up. The striking of the side is a commemoration of the passion of Christ, from whose wound our salvation flowed. And to us, too, who are held by the chains of pressures, the apostle Peter himself gives such solace, saying: "Since Christ suffered in the flesh, arm yourselves also with the same intention" (1 Peter 4). — Commentary on Acts Oecumenius : He says that it shone so that they could both see and hear Peter and not think it a vision. The phrase "quickly [ἐν τάχει]" does not mean making a noise, but persuading not to delay. [CHRYSOSTOM] — Commentary on Acts