Keith Simons teaches on Psalm 137, emphasizing its prophetic nature and the deep sorrow of the Israelites in Babylon after the destruction of Jerusalem. He explores the contrast between the luxury of Babylon and the mourning of the captives who long for their homeland, highlighting the significance of remembering Jerusalem. Simons suggests that the psalm serves as both a lament and a prophecy, reflecting the hope of restoration and God's judgment against oppressors. He encourages a deeper understanding of the text within the context of the King James Version and its historical implications. Ultimately, the message conveys the importance of remembering God's promises and the future restoration of His people.