In Aseres HaDibros, HaShem promises long life to those who fulfill the mitzva of respecting their parents. Conversely, Chazal say that the lifespan of Yosef HaTzaddik was shortened because of a disrespectful gesture he expressed towards his father. Ten times during the dialogues between Yosef and his brothers, the shvatim referred to their father Yaakov as ‘your servant, our father’ – and although Yosef heard, he remained silent. Since silence can be interpreted as agreement, his life was shortened by ten years.
Moreover, the AriZal writes that tzaddikim in Gan Eden are judged even for things they may have done as young children, as young as seven or eight years old.
R. Yehuda Hachossid writes: When the Torah tells us how Eisav returned exhausted from hunting, it adds the description, ‘He felt as if he were about to die.’ With these words, the Torah is letting us know that the descendants of Eisav have merited their power because he endangered his life to hunt for his father. From this we must take a lesson as to how much exertion must be invested to sustain our parents.
The Rambam states: If a person does not respect his parents, his children will not respect him.
Rebbi Meir taught: "The Torah commands us to honor our father and mother, and a king’s command applies more rigorously inside his palace than outside it. So if HaShem has commanded people who are outside his palace to honor their father and mother, how much more so does this command apply inside His palace – Gan Eden. However, if someone's sons are sitting among the tzaddikim in Gan Eden and their father is among resha’im, this is surely no way to fulfill the mitzva of respect."
After quoting this teaching, Reishis Chochma concludes: "Therefore, in the zechus of the son's good deeds, the father is saved and he, too, is ushered into Gan Eden."
To this the Rebbe Rashab adds that the main mitzva through which a son saves his father is the mitzva of kibud av va’eim. That is why Rebbi Meir learned the above concept, of how the zechus of a son saves his father, specifically from this mitzva.