Acts 5:17–42 (ESV)

17 But the high priest rose up, and all who were with him (that is, the party of the Sadducees), and filled with jealousy

The continued growth of the church, the teaching about Jesus, and the popularity of the apostles forced the Jewish elite to take action. They were jealous of the apostles’ success and furious that they had ignored the instructions of the Sanhedrin. Further action was now needed to stop the growth of the new movement.