Why did Sejong let Yan Song retire and exiled Yan Shifan to Leizhou?

Sejong asked, "Why isn't Fang peaceful today?" At this moment, knowing that Sejong was dissatisfied with Yan Song, Landaoxing put Yan Song and his son's sin under false divination. Sejong said, "If so, why didn't Shang Xian get rid of it?" Landaoxing said in Fu Ying's mouth: "The immortal should be left to the emperor to get rid of himself." Zou Yinglong learned this from eunuchs, and thought it was time to get rid of rape. So he went to Shu, listed the sins of Yan Song and his son and Yan family, and pointed out that their family was so evil. "The people are not poor, the national security is inexhaustible, and the demon disaster is alert!" On the hydrophobic "zong" Yan Song abdicated, Yan Shifan demoted Leizhou.