Genesis 29:22-26

So Laban gathered all the people of the place and held a feast.

Now in the evening he took his daughter Leah and brought her to him; and Jacob had relations with her.

Laban also gave his female slave Zilpah to his daughter Leah as a slave.

So it came about in the morning that, behold, it was Leah! And he said to Laban, “What is this that you have done to me? Was it not for Rachel that I served with you? Why then have you deceived me?”

But Laban said, “It is not the practice in our place to marry off the younger before the firstborn.