Zhu Xiushi made a valid point and used sealing arts to persuade Lu Bei. The latter didn't want to start a war, but he also didn't want to leave the treasure mountain empty-handed and let Xiongchu reap all the benefits.
Both sides took a step back: Lu Bei would immediately go to the Heavenly Sword Sect to rally people, and three days later, regardless of their gains, they would immediately withdraw from Xiongchu.
The three-day timeframe wasn't chosen at random.
Chapter 633