The Jewish leaders realized that Peter and John had been associating with Jesus.

Acts 4:13-14

13 The Jewish leaders realized that Peter and John ◄were not afraid of them/spoke boldly►. They also learned that the two men were ordinary people who had not studied in schools. So the leaders were amazed, and they realized that these men had associated with Jesus. 14 They also saw the man who had been healed standing there with the two of them, so they were not able to say anything to oppose Peter and John.