1,008. Violating the Torah
143:10 If one sees his parent violating a Torah law, he may not say outright, "You have violated a Torah law." Rather, he should ask, "Father, doesn't the Torah say such-and-such?" By appearing as if he is seeking information from his parent and not reprimanding him, the parent will get the message and will not be embarrassed.
143:11 If one's parent told him to transgress a Torah law, whether a positive or a negative mitzvah, or even a rabbinic law, he may not listen to him as per Leviticus 19:3, "Every person must revere his mother and father, and keep my Sabbaths; I am Hashem, your G-d." Juxtaposing Shabbos with obeying our parents tells us that even though we must listen to them, if they say to desecrate Shabbos, we don't listen. The same is true with all the other mitzvos because "I am Hashem, your G-d" - both you and your parents are obligated to honor Me, therefore you may not listen to him to ignore My words. Rabbinic mitzvos are also mitzvos of Hashem as per Deuteronomy 17:11, "You shall not deviate" (from what the Rabbis instruct).
If one's parent told him not to speak with a particular person, nor to forgive him, and the son wants to make peace, he should not listen to his parent. This is because we are forbidden to hate another Jew unless we saw him sinning. Therefore, the parent's instructions would be ordering him to violate a law of the Torah.