They only heard the account: "The man who formerly persecuted us is now preaching the faith he once tried to destroy."

Acts 6:7
So the word of God continued to spread. The number of disciples in Jerusalem grew rapidly, and a great number of priests became obedient to the faith.

Acts 9:21
All who heard him were astounded and asked, "Isn't this the man who wreaked havoc in Jerusalem on those who call on this name? And hasn't he come here to take them as prisoners to the chief priests?"

Acts 19:13
Now there were some itinerant Jewish exorcists who tried to invoke the name of the Lord Jesus over those with evil spirits. They would say, "I bind you by Jesus, whom Paul proclaims."

Galatians 6:10
Therefore, as we have opportunity, let us do good to everyone, and especially to the family of faith.

But they had heard only, That he which persecuted us in times past now preaches the faith which once he destroyed.