Being grieved that they taught the people, and preached in Jesus the resurrection from the dead:

“Peter, together with John, preached to them this plain message of glad tidings, that the promise which God made to the fathers had been fulfilled by Jesus; not certainly proclaiming another god, but the Son of God, who also was made man, and suffered; thus leading Israel into knowledge, and through Jesus preaching the resurrection of the dead, and showing, that whatever the prophets had proclaimed as to the suffering of Christ, these had God fulfilled.”

“Which very thing, too, we observe to come from divine authority, that the priest should be chosen in the presence of the people under the eyes of all, and should be approved worthy and suitable by public judgment and testimony; as in the book of Numbers the Lord commanded Moses, saying, "Take Aaron thy brother, and Eleazar his son, and place them in the mount, in the presence of all the assembly, and strip Aaron of his garments, and put them upon Eleazar his son; and let Aaron die there, and be added to his people." God commands a priest to be appointed in the presence of all the assembly; that is, He instructs and shows that the ordination of priests ought not to be solemnized except with the knowledge of the people standing near, that in the presence of the people either the crimes of the wicked may be disclosed, or the merits of the good may be declared, and the ordination, which shall have been examined by the suffrage and judgment of all, may be just and legitimate. And this is subsequently observed, according to divine instruction, in the Acts of the Apostles, when Peter speaks to the people of ordaining an apostle in the place of Judas. "Peter," it says, "stood up in the midst of the disciples, and the multitude were in one place." Neither do we observe that this was regarded by the apostles only in the ordinations of bishops and priests, but also in those of deacons, of which matter itself also it is written in their Acts: "And they twelve called together," it says, "the whole congregation of the disciples, and said to them; " which was done so diligently and carefully, with the calling together of the whole of the people, surely for this reason, that no unworthy person might creep into the ministry of the altar, or to the office of a priest. For that unworthy persons are sometimes ordained, not according to the will of God, but according to human presumption, and that those things which do not come of a legitimate and righteous ordination are displeasing to God, God Himself manifests by Hosea the prophet, saying, "They have set up for themselves a king, but not by me."”

“"Being grieved that they taught the people." Not merely because they taught, but because they declared, not alone that Christ Himself was risen from the dead, but moreover, that we through Him do rise again. "Because they taught the people, and preached through Jesus the resurrection of the dead." So mighty was His Resurrection, that to others also He is the cause of a resurrection. So then at first they did all for the sake of man's opinion or glory: but now another motive was added: that they should not be thought guilty of murder, as they said subsequently, "Do ye wish to bring this man's blood on us?" O the folly! Persuaded that He was risen, and having received this proof of it, they expected that He Whom death could not hold, could be cast into the shade by their machinations! What can match the folly of this! Such is the nature of wickedness: it has no eyes for anything, but on all occasions it is thrown into perturbation. Finding themselves overborne, they felt like persons who have been outwitted: as is the case with people who have been forestalled and made a sport of in some matter.”

“Being grieved that they taught the people,.... Any doctrine, and especially that which follows, and which particularly gave uneasiness to the Sadducees, they were exceedingly distressed by it; it pained them to the very heart, and they were filled with wrath and indignation: and preached through, or in Jesus, the resurrection of the dead; they not only preached the doctrine of the resurrection of the dead in general, but gave an instance and proof of it in the resurrection of Christ, affirming that he was risen from the dead; and they also preached up the resurrection of the dead in his name, and asserted, that he would be the author of it, and it would be erected by his power: so that their doctrine was equally disagreeable to the Pharisees and Sadducees; to the Sadducees, who denied that there was, or would be any resurrection of the dead; and to the Pharisees, who though they believed it, yet were highly offended that it should be said, that Jesus was risen from the dead; and that the general resurrection of the dead should be attributed to him.”