What is the significance of 2 Samuel 24:17–25?

“So the Lord answered [David’s] supplication for the land, and the plague was averted from Israel.”

The passage suggests that the Lord intended the plague to judge Israel further but David’s supplication persuaded him to change his mind and relent from his punishment. If the future is to some degree open and God is genuinely affected in the present by what we do and by how we pray, the urgency the Bible attaches to prayer begins to make sense. If everything is eternally settled, this urgency is compromised.