Kangxi is a very clever man. He went to the donation ceremony in person because he was afraid that he would miss it if he went late. Because if it is an imperial edict, it is possible that the executioner will deny it and then kill the person directly.

1, Zhang is a difficult person.

As we all know, Zhang's brother was beheaded for offending people in the imperial court. At that time, Emperor Kangxi didn't think so much, but felt that many ministers impeached him. I think he did do something bad. What he didn't expect was that these ministers joined forces to deal with Zhang, and later someone helped Zhang rehabilitate. Tell Kangxi what happened before Zhang's execution. So Kangxi also felt very remorseful, fearing that others would not listen to his instructions and kill people directly, so he had to go in person. This situation is very common in history. Before the execution, they can say that they killed people before they heard the news, so they shirked their responsibilities in this way.

Kangxi is willing to believe Zhang's words.

At that time, Kangxi's sons tried every means to compete for the throne, including bribing people around the emperor and helping them put in a good word. So at that time, Emperor Kangxi didn't trust the people around him, so he would rather trust his brother Zhang. In order to prevent others from hurting Zhang, he had to go to the altar to rob someone himself. Because it's the only way to keep him safe.

To sum up, Kangxi went to the ceremony in person because he was afraid that someone would do something bold, so he felt that verbal instructions were not safe.