Q. On 828 we were asked:“Rashi (21: 18) quotes Talmud (Sanh. 71b) that the wayward and rebellious son is executed on account of what he will do in the future.
Baalei Mussar and others argue that if this applies to future wrongdoings, it surely should hold true for mitzvos to be done in the future, as long as there is a certainty that they will be so done, (as opposed to Yishmael who was judged only “Baasher Hu Shom,” since the crimes to be committed were by his descendants). According to this opinion, we must wonder, how long does one have to be doing a mitzva for it to be considered as a sure thing so one can already now be given the credit of the future? This can make a tremendous difference on the judgment of the Yemei Hadin.”
A. “Indeed we do find that in merits, Hashem does consider the future good deeds to be done already now. Rashi (Shemos 3: 12) writes; Concerning what you asked, “What merit did the Bnei Yisroel have that they should go out of Mitzrayim? The answer was: I have a great thing depending on this exit, for at the end of three months from their exit from Mitzrayim, they are destined to receive the Torah on this mountain.”
Rabbi A. Bartfeld as revised by, Horav Yaakov Hirschman, Horav Dovid Pam, Horav Aharon Miller, Horav Chanoch Ehrentreu and Horav Kalman Ochs Shlit'a