shtikl dvar Torah on vayigash: from bikorei shimo by R’ Shmuel Birnbaum ZTL his yartzeit is not too far away. He quotes the Bais HaLevi: why did Yosef say “ha’od avi chai” and not “avinu?” and also, why were the shevatim so concerned with the tzaar that Yaakov will have if Binyamin isnt safe and not with Yaakov’s extreme tzaar when he found out Yosef was “dead?” their behavior is a stirah.
so the Bais HaLevi answers that the shevatim thought because there are 12 of them, if Yosef is gone, the remaining 11 can “make up” for him and fill his place. Yosef is saying, youre wrong!! it duznt matter how many children a father has, theyre each a special and unique son to their father and can NEVER be replaced. this is why Yosef said “avi” becuase he was letting them know that they were wrong in assuming Yosef could be replaced–because “avi” is his personal father.
same with us–we cant say, its okay if i dont learn tonight because theres thousands of beis midrashim learning instead of me…i dont need to do this particular mitzvah, im sure there are many out there who are doing it…this is WRONG we are each individual children to Hashem and He treats us like that so we need to act like it—thats why the Medrash says “oy lanu yom hadin, oy lanu yom hatochacha”–becuase this is what will happen, well see we were wrong in assuming that we can be lax about things when we are being judged