Deuteronomy 5:10 ..."To those who keep His commandments...God's grace is extended to a thousand generations", Rashi's comment suggests when obeying out of fear. Deuteronomy 7:9..."Those who love Him...it is extended to thousands of generations", Rashi's comment suggests when obeying out of love for God. If a generation is reckoned 25 years, we're talking of 25,000 years (a thousand) or more (thousands). Will we have off spring in olam haba or will Israel last that long on this earth ?
I don't have a source, but I think that it means "descendants". The good is promised "wide" - as much as the family tree spreads out, while the bad is four generations "deep", irrespective of how many people that might be.– simyouAug 6, 2020 at 10:46
@simyou. Your 2d interpretation holds the water better as in the 1st version you give, the complication arises with so many ancestors for the guy, say, of the 20 th generation or worse of the 1000 th generation, how are handled down all these curses and blessings from a mixed ancestry (merit wise) ?– Pioni5777Aug 7, 2020 at 16:05
The Chatam Sofer asks your question on Exodus 20:5, which promises reward to thousands of generations, based on the Gemara (Rosh Hashana 31a) that the world will only last 6000 years, which isn't long enough for thousands of generations to pass.
He quotes the Shoshanim LeDavid, based on the Bahag, who answers that a generation can be as short as 2 years long. The Chatam Sofer isn't satisfied with this answer because the 26 generations from Adam until the giving of the Torah were clearly longer than 2 years. Also, the three or four generations of retribution in the preceding verse are literal generations, because (as Onkelos translates) this only applies if the sons continue to act like their fathers.
His own answer is a very cryptic hint to the shemittah. I don't understand exactly what he means, but I can only guess that he's hinting to something along the lines of the Rikanti (Parashat Behar) that the world will last for additional years corresponding to the yovel (seven shemittot) or even a "great yovel" of 1000 generations.
@b a. Much food for thought, thanks. With the Chatam Sofer you seem to lean on the side of the literal acounting of generations. So, how do you answer my query: pru vru in olam haba or extension of Israel's sojourn on this earth to allow these promises to take pla ce ? Aug 7, 2020 at 16:12
@Pioni5777 His answer is too cryptic for me to be able to deduce his opinion on that. But Berachot 17a is relevant: הָעוֹלָם הַבָּא אֵין בּוֹ לֹא אֲכִילָה וְלֹא שְׁתִיָּהּ וְלֹא פְּרִיָּה וּרְבִיָּה "In the World-to-Come there is no eating, no drinking, no procreation"– b aAug 8, 2020 at 17:47