'Eldest' in the Bible

Abraham said to his servant [Eliezer of Damascus], the oldest of his household, who had charge over all that Abraham owned, “Please, put your hand under my thigh [as is customary for affirming a solemn oath],

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].

The steward searched, beginning with the eldest and ending with the youngest, and the cup was found in Benjamin’s sack.