"And God saw their works, that they turned from their evil way; and God repented of the evil, that he had said that he would do unto them; and he did it not.” - Jonah 3v10
What was it that spared the city of Nineveh from the judgement that God had planned? They were certainly on God’s judgement list for their sins – they only had thirty days to repent or destruction was coming. However they heard Jonah’s message and responded – they turned to God.
Some have claimed that the revival was not genuine, that it was only a response to being afraid of God’s wrath. Yet. God spared them from the wrath that was planned for them – something must have happened.
I believe that Nineveh saw a genuine turning to God. Why? Because God saw their works - that they repented of the evil that they had down. True repentance is going to manifest itself in good works. God could not be tricked – He knew that they had repented because their lives changed.