Get in line, recruits! Psalms 137 is all about how the Israelites feel about being in exile, and their longing to return to their homeland. They remember the good times in Jerusalem, and they know they can never go back, so they feel sad. The Israelites say they will never forget Jerusalem and they will never stop singing songs about it. They also say that if they ever do go back, they will take revenge on the people who made them leave. That's Psalms 137! Dismissed!