Acts 9:1 reveals Saul's murderous threats — the stark contrast with his current preaching explains the listeners' astonishment.

Acts 9:2 details Saul's mission to arrest believers — the very plan that makes his current preaching so shocking.

In Acts 9:13, Ananias confirms the rumor: Saul's past evil against Jerusalem's saints is the reason for the amazement in Acts 9:21.

Acts 9:14 adds that Saul has official authority from chief priests to arrest believers, explaining why he came to Damascus.

Acts 8:3 depicts Saul's ravaging of the church—the very 'havoc' that his hearers are recalling in Acts 9:21.

Acts 7:59 records Stephen’s martyrdom, where Saul was present (Acts 7:58), grounding the 'havoc' reputation in Acts 9:21.

Acts 22:4 quotes Paul confessing his persecution of the Way, directly matching the 'prisoners to chief priests' description in Acts 9:21.

Acts 26:10 adds Paul’s own detail of imprisoning saints and voting for their death, confirming the devastation implied in Acts 9:21.

Acts 3:10 records amazement at the healed beggar's transformation — here, similar astonishment at Saul's radical change from persecutor to preacher.

Matthew 13:55 uses the same 'Isn't this...?' rhetorical question pattern — questioning how someone with a known past can be different now.

John 9:8 has the identical 'Isn't this the man who...?' question — neighbors recognizing the healed blind man, mirroring the recognition of Saul.

Galatians 1:13-24 provides Paul’s own account of his former persecution and the amazement of churches, echoing Acts 9:21’s theme.

Mark 5:15-20 describes the transformed demoniac astonishing the townspeople — a parallel to Saul's dramatic change and new witness role.

Matthew 13:54 shows people amazed at Jesus' wisdom — here, amazement at Saul's preaching, both questioning the source of newfound authority.