This was not a quiet miracle! The man was jumping around, praising God. He was active and noisy -- the perfect attraction for a large crowd. And Peter exploited it for eternity's sake.
The sermon was amazing. His citations of the Old Testament are masterful. He hits the high points. I'm sure they were points Jesus had hit just days before when he opened their eyes to understand the scriptures (Luke 24:45). He referred to God's covenant with Abraham, he spoke of Moses' promise of a prophet like him. He brought in Samuel. He referenced God's self-revelation in Exodus 3.
His conclusion was the elephant in the room -- or the temple as the case may be -- these people killed the man in whose name the lame man was healed!