The sentence in this excerpt from Leo Tolstoy's The Death of Ivan Ilyich that shows that Ivan Ilyich's son is still innocent and uncorrupted is "His son had always seemed pathetic to him, and now it was dreadful to see the boy's frightened look of pity".
In this novella by Leo Tolstoy, Vasya, Ivan Ilyich's son, is presented as an uncorrupted character. He is the one who actually feels sad for his father's suffering before he dies at the end of the book. At the same time, Vanya is one of the few characters whom Ivan feels compassion for since his son has not fallen into the trap of a society full of inauthentic people. In other words, Vanya is presented as a genuine and caring child: he remains innocent in a society where everyone is false.