In this verse we find, in simple words, the true philosophy of all persecution.
I. The authorities were offended because the Apostles taught. (1) They considered that the Apostles were not personally qualified to discharge the important duties of public teachers. Human nature is ever the same. The priests are still grieved that men who are no scholars should undertake to decide what is truth and what is error. (2) The authorities were further of opinion that the Apostles were not only disqualified educationally, but that they had no official right to teach. The priests claimed an exclusive right to teach. This, however, had not always been the case in Jewry. The rights and ceremonies of religion only had been deposited in the safe keeping of the priests; the teaching of the people was entrusted principally to the prophets. When prophecy died out, the priests assumed the functions of the prophets, and, at length, came to look upon themselves as the only rightful teachers of the nation.
II. The authorities were offended because the Apostles taught the people. (1) Some felt grieved on personal considerations; for the Apostles, labouring to enlighten and convert the people were undermining the power of the priests. (2) Others felt annoyed on ecclesiastical grounds. (3) Others felt annoyed on civil grounds.
III. The authorities were enraged with the character of the Apostles' teaching. (1) It reflected deep discredit on the tribunals of the nation. (2) Their teaching, moreover, was new, and the Pharisees were very much in love with the old. (3) Their teaching flatly contradicted that of an influential section of the hierarchy. The Sadducees felt aggrieved that they should preach "by the example of Jesus the resurrection from the dead." But the imprisonment of the Apostles did not check the mighty progress of the Gospel. Rather did it help it forward. Times of persecution are generally times of much spiritual prosperity.
J. Cynddylan Jones, Studies in the Acts,p. 70.