פירוש על קידושין 63:13

Do not speak to your father like that: To suddenly inform him that he is mistaken; that you said to him, "Do not teach it this way,"

This is what is written in the Torah? He will cause him suffering: And behold, it is as if he is saying to him, "You have transgressed the words of the Torah."

This verse is written in the Torah: And he says to him the verse as it is written; and [the father] will understand by himself that he erred.

Shmuel rebukes R. Judah, whom he calls “toothy one” for speaking so directly to his father. One is allowed to tell one’s father that he has done something wrong—but he must say so in a very indirect manner, one that will not cause the father grief.