How did Yan Song provoke the relationship between Xia Yan and Sejong?

Yan Song lost no time in grasping Sejong's tendency to be more and more partial to himself and his dissatisfaction with complicated characters, slandered Xia Yan, and provoked the relationship between Xia Yan and Sejong, saying that Xia Yan wanted to isolate Sejong and was glad that no one was willing to contribute to Sejong. However, with the support of Xia Yan at that time, Yan Song dared not offend Xia Yan openly, and pretended to be humble and humble on the surface, just like his son served strict father, and he was obedient everywhere. In order to paralyze Xia Yan, he also wrote many beautiful poems to praise Xia Yan. The more Yan Song praised The Last Month Of Summer, the more Xia Yan despised him. Especially when Yan Song was found to belittle him in the dark, it was an insult to Yan Song, and Yan was regarded as a public guest. In order to show his courtesy, Yan Song has hosted many banquets, prepared delicious food, invited Xia Yan to dinner, and sometimes personally went to Xia Yan's house to read the invitation, but Xia Yan always refused to go, sometimes promised to go to dinner, and then made excuses not to go, making Yan Yan's family as busy as a bee.