One day, six months later, Bo Jie told Mao Xiaohong that he'd seen a faint shadow climb onto a peer and then jump into a river to his death. Mao Xiaohong didn't pay much attention at the time; he thought it might just be fate—a Wronged Ghost searching for a substitute to die in its place before reincarnating, with the deceased then waiting three years to find their own replacement. Such matters are not interfered with by cultivators; that's just how life is. If one were to meddle, it would go against the will of the heavens.
Perhaps Mao Xiaohong hadn't made it clear to Bo Jie, who the very next day sneaked into the woods where he'd seen the apparition and foolishly waited. Since his master would not deal with it, he'd rely on his own strength to subdue it, hoping to impress his master afterward.