In Zhao Wei's Princess Zhu Huan, which passage is Wei Zi and the emperor traveling incognito?

One day, a group of people were watching in a crowded market. Wei Zi and Gan Long met an old couple selling tea eggs. Suddenly, they took out a pre-stored short knife and stabbed Gan Long. At that time, the situation changed. People in the city became assassins and often attacked Gan Long. Wei Zi saw that the situation was urgent and desperately went to find a knife for Gan Long.