Acts 5:32

The apostles thought of themselves not just as heralds of good news but as eyewitnesses of that to which they now testified. The witness of the Holy Spirit to which Peter referred was evidently the evidence that Jesus was the Christ that the Spirit provided through fulfilled messianic prophecy. The apostles saw themselves as the human mouthpieces of the Holy Spirit whom Jesus had promised to send to bear witness concerning Himself (John 15:26-27). They announced the fulfillment of what the Holy Spirit had predicted in the Old Testament, namely, that Jesus was the promised Messiah. Furthermore God had now given the Holy Spirit to those who obeyed God by believing in Jesus (John 6:29). The Holy Spirit was the greatest gift God gave people who lived under the Old Covenant (cf. Luke 11:13). These leaders needed to obey God by believing in Jesus and then they too would receive this wonderful gift.

The early gospel preachers never presented belief in Jesus Christ as a "take it or leave it" option in Acts. God has commanded everyone to believe in His Son (e.g., Acts 2:38; Acts 3:19; Acts 17:30). Failure to do so constitutes disobedience and results in judgment. The Holy Spirit now baptizes and indwells every person who obeys God by believing in His Son (John 3:36; John 6:29; Romans 8:9). This must be the obedience Peter had in mind.