Genesis 29:19

It is better that I give her to thee. — It is still the custom among the Arabs to prefer a relative as the husband of a daughter, and on giving a moderato dowry the elder cousins can claim the elder daughters in marriage, and the younger the younger. Thus Jacob, as the second son, had a claim upon Rachel. The Rabbins even say that Leah’s eyes were weak from weeping, because Esau had not come to marry her. This absurd idea bears witness, nevertheless, to the custom of the intermarriage of cousins being an established rule, and gives a reason for Laban’s acceptance of Jacob as the husband of his younger child. As Jacob offered seven years’ service for Rachel, and gave a second seven years’ service for her after he had been tricked into taking Leah, we may conclude that the length of time was not unreasonable.