One family member is quite literate. When he first took a children's exam, what was the classical Chinese that his father ordered to recite?

It is a short story named "Don't Grind Ink" in the joke collection "Laugh Well" by Shi, a writer in Qing Dynasty.

Original text:

One family member is quite literate. When I first went to the children's trial, my father ordered him to recite the text, saying that he would be the first choice, which he did not record. Father's responsibility, so that the county Yin, Yin Cha original volume, but the pen as light as fog, flickering, beyond recognition.

The father went home angrily, punished his son for kneeling at the foot of the steps, and sharply questioned him. Yes, he said, "Because there is no boy grinding ink for me in the examination room, he just writes on a black inkstone, so he is weak."

Translation:

There is an aristocratic boy who is very capable of writing articles. After taking the children's exam for the first time (the initial imperial examination), (his) father asked him to recite (the article). He thought it must be his first choice (after listening), but he was admitted only after writing a list. Father felt strange and asked the county magistrate. The magistrate looked at the original paper, and it turned out that the pen and ink used to write were as light as mist. Even if there is, it is difficult to identify.

The father came home angrily, punished his son, made him kneel at the foot of the steps and asked him sharply. (Son) Answer: "Because there is no boy servant in the examination room to help me wipe the ink, I have to write in black ink stone, so (the word) is weak."