Comentario citado sobre Génesis 16:5

ותאמר הנה אמתי, She said: "here is my bondwoman, etc." She was careful to say: "my bondwoman Bilhah," before mentioning that Jacob should sleep with her, instead of saying: "sleep with my bondwoman Bilhah," as Sarai had done at the time (Genesis 16,2). I have explained there that Rachel did not mean for Bilhah to be still called a bondwoman after she had slept with Jacob. She gave Bilhah to Jacob to become a wife to him; any sons of her should be free men. Leah acted similarly when giving her bondwoman Zilpah to sleep with Jacob.

"She conceived ב''פ" (in the second month) in the portion. From here, there is a hint to Rashi's commentary that the evil eye affected her and caused her to miscarry, and then she became pregnant again."

In short, we could say that Yitzchak led an ivory-tower spiritual existence. Such a view helps answer a major question asked by Ramban: Why did Rivka have to deceive Yitzchak rather than explain to him the correctness of blessing Yaakov and not Esav? The implicit basis for this question was later elaborated on by the famous nineteenth century Rosh Yeshiva, Netziv (Rabbi Naftali Tzvi Yehudah Berlin). He says that Rivka behaves completely differently from the other mothers (i.e., Sarah and Rachel) when they disagreed with their husbands’ actions. We see that the other mothers felt it their prerogative to challenge their husbands’ views on a number of occasions.¹⁰Most pointedly in Bereshit 16:5, 21:10 and 30:1. When we consider Yitzchak’s unique character, however, a likely reason for Rivka’s equally unique behavior emerges: it could be that she sought to preserve Yitzchak’s ivory-tower existence, an existence he did not share with Avraham or Yaakov. Rivka thus wanted to shelter him from the more sordid facts about their son Esav.¹¹See Haamek Davar on Bereshit 27:46. In this, she seems to emulate God Himself Who, as explained earlier, also sheltered Yitzchak from too much exposure to the difficulties of life. While it was important to Rivka that Esav not get the blessing, she orchestrated it in such a way as to keep Yitzchak innocent and pure. Indeed, the rabbis refer to Yitzchak as an olah temimah – a pure (unblemished) sacrifice. This purity is invoked as the reason he could not go outside of Eretz Yisrael (Bereshit Rabba 54:3), and presumably it is also this purity that Rivka was trying to protect.