Acts
King James Version (KJV)

“And immediately the angel of the Lord smote him, because he gave not God the glory: and he was eaten of worms, and gave up the ghost.”
King James Version (KJV)
12:23 And immediately - God does not delay to vindicate his injured honour; an angel of the Lord smote him - Of this other historians say nothing: so wide a difference there is between Divine and human history! An angel of the Lord brought out Peter; an angel smote Herod. Men did not see the instruments in either case. These were only known to the people of God. Because he gave not glory to God - He willingly received it to himself, and by this sacrilege filled up the measure of his iniquities. So then vengeance tarried not. And he was eaten by worms, or vermin - How changed! And on the fifth day expired in exquisite torture. Such was the event! The persecutor perished, and the Gospel grew and multiplied.
Ac 12:23 The angel of the Lord smote him. Josephus says he lingered five days in great agony. This harmonizes with Luke's account. He was eaten of worms. Josephus says he was taken with abdominal pains; Luke explains the cause. The disease is by no means unknown. Many cases of death from the same cause are on record. Among others the Emperor Galerius, the predecessor of Constantine the Great, so died.