After Emperor Taizong ascended the throne, Li Shimin became prosperous and the people were happy, which was called "Zhenguan rule" in history. Emperor Taizong was very happy. But he killed too many people while fighting for his country, and he felt a little uncomfortable; Especially after killing his brother and younger brother in the Xuanwu gate incident, he is always suspicious and restless.

One night, in a dream, Li Shimin suddenly heard a strange cry outside the door. After a while, he heard heavy footsteps on the roof, knocking at the door and knocking at the window. Li Shimin called the guards at once. They haven't found anything recently. But as soon as Li Shimin fell asleep, those strange voices sounded again, scaring Li Shimin to hold on to the corner and even dare not make any noise. In this way, the sound didn't stop until the cock crowed.

At dawn, Li Shimin called eunuchs and maids to ask, but these people said they heard nothing. Li Shimin felt very strange and always felt that there was a ghost at work.

The next night, the situation was the same as the night before, and the same was true on the third and fourth days ... for seven nights. On the eighth day, early in the morning, Li Shimin couldn't bear it any longer, and involuntarily told Wenwu Baiguan about the fright every night. At this moment, Qin went out to play: "I have killed countless people in my life. If I pile up the bodies, they will be as big as mountains. But I've never seen a ghost. So I never believe in ghosts and gods. I am willing to serve with General Jingde for a long time tonight, and we will see what it is. " Hearing this, Li Shimin was very happy and agreed.

That night, wearing armor, Qin He stood outside the palace gate. Li Shimin was steadfast, didn't get suspicious, didn't hear any sound, and could go to bed.

He said that Qin and two people were rewarded, and a lot of gold, silver and jewels were rewarded. He also praised them and said, "The two generals are really door gods!" Then, I found a lot of painters and drew. Also hanging portraits around the palace gate, Li Shimin thought it could also exorcise evil spirits.

Later generations don't know that Li Shimin once had auditory hallucinations because of mental stress, and really thought that the gatekeeper could keep a family safe and away from ghosts. In this way, we inherited the practice and regarded Qin He as a keeper. During the Spring Festival, we will also hang their portraits at home.