Three days and nights

The sunlight slowly came in from the door of the Bai family's main hall, shining on Chen Baixuan's childish but gloomy face. The day before yesterday, he accidentally left the formation, but he didn't expect to hear that kind of sound coming from Bai Jie'er's room.
Although Chen Baixuan, who had been hanging around outside for a long time, was still young, he knew very well what the sound meant. He listened carefully and was surprised to find that it was his master who was doing that kind of...