Acts 5:19

But the angel of the Lord,.... Or "of God", as the Arabic and Ethiopic versions read, whether Michael, as some have thought, or Gabriel, or what particular angel, is not material to know.

But the angel of the Lord - This does not denote any “particular” angel, but simply an angel. The “article” is not used in the original. The word “angel” denotes properly a “messenger,” and particularly it is applied to the pure spirits that are sent to this world on errands of mercy. See the notes on Mat 1:

THE second persecution of the Church, in which all the Apostles were put into the common prison, was mainly brought about by the sect of the Sadducees. These, as you know, were the Broad School, the liberals, the advanced thinkers, the modern-thought people of the day. If you want a bitter sneer, a biting sarcasm, or a cruel action, I commend you to these large-minded gentlemen. They are liberal to everybody, except to those who hold the Truth of God—and for those they have a reserve of concentrated bitterness which far excels wormwood and gall.

THE second persecution of the Church, in which all the Apostles were put into the common prison, was mainly brought about by the sect of the Sadducees. These, as you know, were the Broad School, the liberals, the advanced thinkers, the modern-thought people of the day. If you want a bitter sneer, a biting sarcasm, or a cruel action, I commend you to these large-minded gentlemen. They are liberal to everybody, except to those who hold the Truth of God—and for those they have a reserve of concentrated bitterness which far excels wormwood and gall. They are so liberal to their brother errorists, that they have no tolerance to spare for evangelicals. We are expressly told that "the high priest, and all they that were with him (which is the sect of the Sadducees) were filled with indignation." That which had been done deserved their admiration, but received their indignation. Such gentlemen as these can be warm at a very short notice when the doctrine of the Cross is spreading and God the Holy Spirit is bearing witness with signs following. Let them display their indignation, it is according to their nature. To them the only answer which God gave was spoken by His angel: "Go, stand and speak in the temple to the people all the words of this life." Argument will be lost upon them—go on with your preaching. They have lost the faculty of believing—go and speak to the people. They are so given over to their doubts, that it is like rolling the stone of Sisyphus to persuade them to faith. They are so eaten up with objections, that to attempt to answer all the questions they raise would be as vain as the labor of filling a bottomless tub. Go on with your preaching, you Apostles—but address yourselves mainly to the people. Extend as widely as possible the range of the Truth of God, and thus answer the opposition of its adversaries. It is better to evangelize than to controvert.

But the angel of the Lord - opened the prison doors - This was done: 1. To increase the confidence of the apostles, by showing them that they were under the continual care of God; and, 2. To show the Jewish rulers that they were fighting against Him while persecuting his followers, and attempting to prevent them from preaching the Gospel. This was another warning graciously given them by a good and merciful God, that they might repent, and so escape the coming wrath.