King Solomon is speaking about the consequences of Joab's past actions, which included the murder of two commanders, Abner and Amasa, during peacetime. Joab's actions were seen as treacherous and unjust, and Solomon, as the new king, seeks to establish justice and order in his kingdom. By calling for the guilt of these actions to remain on Joab and his descendants, Solomon is making a clear statement about accountability and the importance of justice.
At the same time, Solomon contrasts this with a blessing for his father David's house, asking for the Lord's peace to rest upon it forever. This reflects the biblical principle that while wrongdoing has consequences, those who seek to live in accordance with God's will can expect His peace and favor. Solomon's prayer for peace upon David's lineage underscores the enduring covenant God made with David, promising that his throne would be established forever. This verse highlights the themes of justice, accountability, and the blessings of divine peace for those who remain faithful to God's promises.