Just as one is obligated to honor one’s parents during their lifetime, one is likewise obligated to honor one’s parents after their passing. One may certainly not disrespect one’s parents after their death.
The Baraita (Kiddushin 31b) states: “Whenever one mentions a Torah saying from his father, one should say, ‘Father would say this and I am the atonement for his rest.’ This means that every time one mentions his father after his passing, one should say, “I am the atonement for his rest.” What one means to say with this phrase is, “Whatever bad occurrence that was supposed to befall to his soul should happen to me.” This means that the son accepts some suffering upon himself so that his father does not suffer and so that no harm befalls him.
What This Means
Maran Rabbeinu Ovadia Yosef zt”l explains that this does not mean that suffering will actually befall the son instead of the father. Rather, this is only meant as a show of respect. Likewise, in the merit of the son saying this phrase, this will serve to protect the deceased father from suffering.
In Sefer Abir Ha’Ro’im (Volume 2), the author explains that the reference to “an atonement for his rest” means that no harm should befall the deceased in his grave. This is because the most crucial time for the deceased to be protected from harm in the grave is during the first year following his passing. It is for this reason that we mention the deceased’s “rest,” i.e. grave, during this period, for this is specifically the time he requires our prayers the most.
When is the Appropriate Time to Mention this Phrase?
Nevertheless, this only applies within twelve months of the father’s passing. After twelve months though, one should say, “My father, of blessed memory.” The reason why after twelve months one no longer recites this phrase is because the wicked are judged in Gehinnom for twelve months; after this time, there is already no purpose in saying these words since in general, one will already have been freed from Gehinnom and nothing bad will befall the soul of his father from this point on.
Nevertheless, Maran Rabbeinu Ovadia Yosef zt”l writes that only time one must say, “I am the atonement for his rest,” and other such honorary phrases is only when one mentions a halachic thought from his father, as per the words of the Baraita, “a Torah saying.” However, when mentioning mundane thoughts and sayings from one’s father, one need not recite these phrases. Similarly, when one mentions a righteous custom that his mother followed, for instance, that she would recite the blessing upon lighting Shabbat candles before actually lighting in accordance with the opinion of Maran Ha’Shulchan Aruch, one must also say these words.