Jonah 3:3-5 This time Jonah obeyed the Lord's command and went to Nineveh, a city so large that it took three days to see it all. On the day Jonah entered the city, he shouted to the crowds. "Forty days from now Nineveh will be destroyed!" The people of Nineveh believed God's message, and from the greatest to the least, they declared a fast and put on burlap to show their sorrow.
Most all of us have heard the story of Jonah... he did want to go to Nineveh and went the in the opposite direction... he was throw over the ship and swallowed by a whale... then he was spit out on the land...and finally he went to Nineveh. Nineveh was an evil, evil city. What God knew is that the people were ready to listen. It says here that the people of Nineveh believed God's message.
There are so many things to learn from Jonah's story... but what I get from this story is that if God tells me to tell somebody about Him, He already knows that they are ready to hear. He already knows that their hearts are open. I do not have to be afraid, I just have to be willing to do what God ask me to do.