מדרש על בראשית 29:17

However, the Holy One, blessed be He, immediately hears the prayer a man whispers in his heart. Whence do we know this? From Hannah, as it is said: Now Hannah, she spoke in her heart (I Sam. 1:13). You may know this also from Rachel and Leah. At first Leah was not considered worthy of marrying anyone but Esau, while Rachel was destined to wed Jacob. Leah would sit at the crossroads inquiring about Esau’s actions, and they would tell her: “Oh, he is a wicked man; he sheds blood and waylays passers-by, he is covered with red hair as a garment and commits every kind of abomination against God.” Upon hearing all of this, she would cry bitterly: “My sister Rachel and I were born of the same womb, yet Rachel is to marry the righteous man and I the wicked Esau.” She wept and fasted until her sight became weak. Hence it is written: And Leah’s eyes were weak (Gen. 29:17). And the Lord saw that Leah was hated (ibid., v. 31). This verse indicates that Esau’s actions were hateful to her. However, when Rachel learned that she was to marry Jacob she was elated and became arrogant. Once they both were married to Jacob, the Holy One, blessed be He, said: She cried, and fasted, and despised Esau’s behavior, and prayed to me. It would be unjust to keep her from the righteous one. Indeed I will let her bear sons first. Thus it is said: And the Lord saw that Leah was hated.

The Lord saw that Leah was hated (Gen. 29:17). Scripture states elsewhere in allusion to this verse: For He knoweth base men; and when He seeketh iniquity, will He not then consider it? (Job 11:11). This verse refers to what happened to Ishmael at the time that Sarah told Abraham: Cast out this bondwoman and her son (Gen. 21:10). This entire matter is described in the verse And Abraham rose up early in the morning and took bread and a bottle of water, and gave it to her, etc. (ibid., v. 14).

Another interpretation: Why was Leah hated? Not because she was more ugly than Rachel. In fact she was as beautiful as Rachel, as stated (in Gen. 29:16). LABAN HAD TWO (ShTY) DAUGHTERS. They were equal (ShWWT) in beauty, in loveliness, and in stature. Why does < Scripture > say (in Gen. 29:17): AND LEAH'S EYES WERE WEAK?³⁴Below, 7:20; BB 123a; Gen. R. 70:16; 71:2. Simply < this > : When Rebekah bore Esau and Isaac, there were born to Laban two daughters, Leah and Rachel. They sent letters to each other and agreed among themselves that Esau would take Leah; and Jacob, Rachel. Now Leah would ask about the conduct of Esau and would hear that his conduct was bad. So she would cry all the time < and > say: Thus my lot has fallen to this wicked man. And for this reason her eyes became weak, as stated (in Gen. 29:17): AND LEAH'S EYES WERE WEAK.