Rabbi Paula Goldberg wrote the following excerpt:
Now Laban had two daughters; the name of the older one was Leah, and the name of the younger was Rachel. Leah had weak eyes; Rachel was shapely and beautiful. Jacob loved Rachel; so he answered, "I will serve you seven years for your younger daughter, Rachel."
Laban said, "Better that I give her to you than that I should give her to an outsider. Stay with me." So Jacob served seven years for Rachel, and they seemed to him but a few days because of his love for her. Then Jacob said to Laban, "Give me my wife, for my time is fulfilled, that I may consort with her."
And Laban gathered all the people of the place and made a feast. When evening came, he took his daughter Leah and brought her to him; and he cohabited with her. (Laban had also given his maidservant Zilpah to his daughter Leah as her maid). When morning came, there was Leah!
So he said to Laban, "What is this you have done to me? I was in your service for Rachel! Why did you deceive me?" Laban said, "It is not the practice in our place to marry off the younger before the older" (Genesis 29:16-26).
Leah was destined to marry Esau and Rachel to marry Jacob. Leah sat at the crossroads asking about Esau, and they told her, "Oh, he's a wicked man." Hearing this, she cried 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 (Tanchuma Vayeitzei 4).
Jacob said to Laban, "Knowing that the people of your town are deceivers, I make my demands absolutely clear." Thus he said, "I will serve you seven years for your younger daughter, Rachel" [Genesis 29:18]--not Leah. "Your daughter"--you mustn't bring some other woman from the marketplace named Rachel. "The younger"--you mustn't exchange their names (Genesis Rabbah 70:17).
Jacob said to Rachel, "Will you marry me?" She answered, "Yes, but Father is a trickster, and you will not prevail against him." He asked, "What is his trickery?" She said, "I have a sister who is older than I; he will not let me marry before she does."
He said, "I am his brother in trickery."
She said to him, "May the righteous indulge in trickery?" "Yes," he replied. "'With the pure, You act in purity, and with the crooked, You are wily'" (II Samuel 22:27). Thereupon he gave her certain identification marks [note: other versions use the word tokens.].
When Leah was led [into the bridal chamber], she [Rachel] thought, "My sister will now be disgraced;" so she gave the marks/tokens to Leah. That explains what is written: "When morning came, there was Leah!" which seems to imply that until then, she was not Leah! Rather, because of the signs that Jacob gave to Rachel, who gave them to Leah, he didn't know who she was until then (Talmud, Bava Batra 123a).
Jacob said to Leah: "You are a deceiver and the daughter of a deceiver!"
"Is there a teacher without pupils?" she retorted. "Didn't your father call you Esau, and you answered him! So did you call me Rachel, and I answered you!" (Genesis Rabbah 70:19).