'Eldest' in the Bible
And Abraham said to the eldest servant of his house [Eliezer of Damascus], who ruled over all that he had, I beg of you, put your hand under my thigh;
When Israel dwelt there, Reuben [his eldest son] went and lay with Bilhah his father's concubine; and Israel heard about it. Now Jacob's sons were twelve.
And [Joseph's brothers] were given seats before him -- "the eldest according to his birthright and the youngest according to his youth; and the men looked at one another amazed [that so much was known about them].
And [the steward] searched, beginning with the eldest and stopping with the youngest; and the cup was found in Benjamin's sack.
When they had come, he looked on Eliab [the eldest son] and said, Surely the Lord's anointed is before Him.
[His] three eldest sons had followed Saul into battle. Their names were Eliab the firstborn; next, Abinadab; and third, Shammah.
David was the youngest. The three eldest followed Saul,
Now Eliab his eldest brother heard what he said to the men; and Eliab's anger was kindled against David and he said, Why did you come here? With whom have you left those few sheep in the wilderness? I know your presumption and evilness of heart; for you came down that you might see the battle.
Then Adonijah son of [David's wife] Haggith exalted himself, saying, I [the eldest living son] will be king. And he prepared for himself chariots and horsemen, with fifty men to run before him.
He said, You know that the kingdom belonged to me [as the eldest living son], and all Israel looked to me to reign. However, the kingdom has passed from me to my brother; for it was his from the Lord.
Then he [Moab's king] took his eldest son, who was to reign in his stead, and offered him for a burnt offering on the wall [in full view of the horrified enemy kings]. And there was great indignation, wrath, and bitterness against Israel; and they [his allies Judah and Edom] withdrew from [Joram] and returned to their own land.
The sons of Judah: Er, Onan, and Shelah, whom Shua's daughter the Canaanitess bore him. Er, Judah's eldest, was evil in the Lord's sight, and He slew him.
And Penuel was the father of Gedor, and Ezer the father of Hushah. These were the sons of Hur, the eldest of Ephrathah (Ephrath), the father of Bethlehem.
Now [we come to] the sons of Reuben the firstborn of Israel. For [Reuben] was the eldest, but because he polluted his father's couch [with Bilhah his father's concubine] his birthright was given to the sons of Joseph [favorite] son of Israel; so the genealogy is not to be reckoned according to the birthright.
And there was a day when [Job's] sons and his daughters were eating and drinking wine in their eldest brother's house [on his birthday],
While he was yet speaking, there came also another and said, Your sons and your daughters were eating and drinking wine in their eldest brother's house,
He leveled and made a straight path for His anger [to give it free course]; He did not spare [the Egyptian families] from death but gave their beasts over to the pestilence and the life [of their eldest] over to the plague.