ציטירנדיקער פּירוש אויף בראשית 30:15

Beneath the sun. Instead [=תַּחַת¹⁹Ordinarily, תחת means “under,” but in this verse that definition would be difficult. Therefore, Rashi interprets תחת as “instead,” as we find in Bereishis 30:15, “in exchange [תחת] for your son’s duda’im.” The Gemara in Maseches Shabbos 30b renders תחת as “after,” and interprets the verse, that for his labor “after the sun” he realizes no profit, but for his labor “before the sun,” i.e., in Torah, which existed before God created the world, there is profit. (Sifsei Chachomim) of the Torah, which is called light,²⁰Mishlei 6:23. as it is stated, “and the Torah is light.”²¹“For all his labor” should not be misconstrued to include even engaging in Torah study, because otherwise Scripture should have stated בכל עמל [=all labor], however it states בכל עמלו [=his labor], referring to his own personal physical labor. Thus, one should labor in the study of Torah. All the labor which he does instead of engaging in Torah study, what reward does it yield?

כי עלית על משכבי אביך, “you went up to your father’s bed;” On which occasion did this take place? At the time when Leah traded Yaakov’s turn to spend the night with Rachel for the mandrakes her son Reuven had found. (Genesis 30,15). (Br’eshit Rabbah 96.4)

Lest we think this is limited to the male gender, the rivalry between Rachel and Leah is hardly less intense, turning sour when Leah accuses Rachel of stealing her husband (Bereshit 30:15).¹¹¹Ibid., 30:15. A husband married to more than one woman is also a zero-sum situation and Leah knows that when Rachel is able to grab Ya’akov’s attention, it will likely come at the cost of time and attention – and perhaps even children – that he might otherwise have given her.