The Haftorah that is read on the afternoon of Yom Kippur tells the story of how G-d commanded the prophet Jonah to go to the city of Ninveh and warn the people there to repent, lest G-d destroy their city.
Jonah did not want to fulfill this mission and ran away on a ship. G-d caused a terrible storm to occur and eventually the sailors threw Jonah off the ship - as the only way to make the storm abate.
G-d caused a great fish to swallow up Jonah. Eventually Jonah was saved from the fish and went to do G-d's bidding in Ninveh.
Why was this story chosen to be read on the holiest day of the year? And why did Jonah "run away" from G-d rather than carry out his mission? To teach us how much our love of our fellow Jew needs to be.
Jonah knew that if he went to Ninveh the people there would repent. He also knew that the Jewish people had not repented in spite of all the chastising the prophets had given them.
Rather than make the Jewish people appear bad in G-d's eyes, Jonah chose to "run away." This lesson is so important that we read it every year on Yom Kippur.