The Gemara in Shabbos (89b) relates what will happen in the End of Days expounding upon the following pasuk:
כי אתה אבינו כי אברהם לא ידענו וישראל לא יכירנו אתה ה' אבינו גאלנו מעולם שמך - “For You are our Father; though Avraham may not know us and Yisroel may not recognize us; You, Hashem, are our Father; our Eternal Redeemer is Your Name” (Yeshayahu 63:16).
Hashem will inform Avraham Avinu that his children have sinned. In defence of Hashem’s honour, Avraham will respond that they deserve to be destroyed.
Hashem will then turn to Yaakov, hoping for a more compassionate response. After all, Yaakov raised twelve shevatim and experienced tzaar gidul banim. Surely, he would find a way to absolve the Jews of their sins. But Yaakov’s response mirrors that of Avraham. Having sinned, the Jewish nation deserves to be wiped out in deference to the honour of the Ribbono Shel Olam.
Hashem then turns to Yitzchak Avinu, and tells him, “Your children have sinned.” Yitzchak responds incredulously, saying, “Are they my children and not Yours? When they lovingly accepted the Torah, promising naaseh v’nishma, did You not refer to them as Bni Bechori?”
Having “reminded” Hashem that Klal Yisroel are His children too, Yitzchak Avinu then makes an astounding calculation. He tallies how much time could have been spent sinning.
He figures that Man lives approximately seventy years, and for the first twenty years he is no subject to punishment biydei Shomayim. This leaves fifty years during which sins could potentially have been committed. Half the time it was night, when Man is sleeping and resting, this leaves the equivalent of twenty-five years in which Man could sin.
Yitzchak then calculated that another twelve and a half years are spent davening, eating, drinking and performing other necessary bodily functions, leaving only twelve and a half years during which Man could have sinned.
Twelve and a half years: That Yitzchak said, was the maximum period of time of sin that could need to be accounted for. Hashem, if You are willing to shoulder all their sins and absolve all this time, then I, Yitzchak Avinu, am willing to split it evenly with You. Palga alai, u’falga alayich – half is on me and half is on you.
Yitzchak continued, if Hashem wants him to bear the full responsibility for the total sin – all twelve and a half years for each person – then he will do so. Klal Yisroel should then be spared in the merit of Yitzchak’s having offered himself as a korban. His willingness to sacrifice his life to fulfil the will of Hashem should provide enough merit to spare the Jewish people from punishment for all of their sins.
Klal Yisroel will immediately begin to praise and thank Yitzchak, telling him ata avinu, you are our father. You defended us, you fought for our existence, and therefore you are truly our father. Yitzchak directs them to express their gratitude to Hashem, and Klal Yisroel then say, אתה ה' אבינו גאלנו מעולם שמך – “You Hashem, are our Father, our Redeemer from time immemorial is Your Name”.
While this entire Gemara requires explanation, we will focus on one part of Yitzchak’s response to Hashem. What did he mean when he said, “palga alai, u’falga alayich, half is on me (Yitzchak), and half is on You (Hashem)”?
