In the breisa of Eilu Devarim that we say each morning after Birchas HaTorah, Chazal list a number of individual mitzvos of which they said that “a person eats their fruits in this world, and the principle remains for him in Olam Haba.” The mitzvah of “Hashkamas beis hamedrash Shacharis v’Arvis” is listed among these mitzvos.
The meaning of this is that for rising to go to shul, a person merits reward already in this world, but that reward is only “peiros”, fruits, but the main reward, “the keren” the principle, is preserved for Olam Haba, where he receives complete and eternal reward.
This uniqueness of eating fruits in this world is only practiced in the few mitzvos that Chazal listed in this breisa, and does not exist with the other mitzvos, where a person only has the keren for Olam Haba. As the Baalei Hatosafos wrote (Bava Basra 10a): “Most of the things do not stand for a person in this world, until after his death. And in olam hazeh, only great mitzvos stand for a person, as it says (Kiddushin 39b): ‘Eilu devarim she’adam ocheil peiroseihem b’olam hazeh vehakeren kayemes lo l’Olam Haba.”
