'Eldest' in the Bible

And Abraham said unto his eldest servant of his house, that ruled over all that he had, Put, I pray thee, thy hand under my thigh:

And it came to pass, that when Isaac was old, and his eyes were dim, so that he could not see, he called Esau his eldest son, and said unto him, My son: and he said unto him, Behold, here am I.

And Rebekah took goodly raiment of her eldest son Esau, which were with her in the house, and put them upon Jacob her younger son:

While Israel was living in that land, Reuben [his eldest son] went and lay with Bilhah his father’s concubine, and Israel heard about it.Now Jacob had twelve sons—

Now Joseph’s brothers were seated [by the steward] before him [in the order of their birth]—the firstborn according to his birthright and the youngest according to his youth; and the men looked at one another in astonishment [because so much was known about them].

And he searched, and began at the eldest, and left at the youngest: and the cup was found in Benjamin's sack.