For he hath broken the gates of brass,.... The prison doors made of brass, as sometimes of iron, for the security of the prisoners; see Ac 12:10. And cut the bars of iron in sunder; with which they were barred and secured.
Hyperbolical phrases these, as Kimchi, expressing how exceeding strong the prison doors were, and the impossibility of an escape out of them, unless the Lord had delivered them; but when he works, none can let; all obstructions are easily removed by him; which is the sense of the words, see Isa 45:2.