Commentary for Kiddushin 78:4
אמר רב יהודה הכי קאמר כל העושה מצוה אחת יתירה על זכיותיו מטיבים לו ודומה כמי שמקיים כל התורה כולה מכלל דהנך אפילו בחדא נמי אמר רב שמעיה לומר שאם היתה שקולה מכרעת
and making peace between man and his neighbour; and the study of the Torah surpasses them all.<span class="x" onmousemove="('comment',' Thus, only for these is one rewarded in this world, whereas the Mishnah states this of any precept. To the Rabbis study was not only a means to religious observance (cf. infra 40b: study is great, as it leads to action) , but a religious act in itself, - indeed, one of the most important, as is shewn by this and numerous other passages in the Talmud. Nevertheless, they were far from believing that religious sincerity might be replaced by mere intellectualism; v. M. Joseph, Judaism as Creed and Life, p. 360.');"><sup>9</sup></span> - Said Rab Judah: This is its meaning: HE WHO PERFORMS ONE PRECEPT in addition to his [equally balanced] merits<span class="x" onmousemove="('comment',' I.e., his good deeds and bad are exactly balanced, and then he performs a precept, thus tipping the scale.');"><sup>10</sup></span> IS WELL REWARDED, and he is as though he had fulfilled the whole Torah.
Daf Shevui to Kiddushin
Daf Shevui to Kiddushin
Since that seems absurd, the Talmud interprets the baraita to say that if one’s merits and faults are even and one of these mitzvoth is part of one’s merits, it tips the scales. But alone, these mitzvoth are not that powerful.