'Thirty' in the Bible
David was thirty years old when he became king, and he was king for forty years,
Ruling over Judah in Hebron for seven years and six months, and in Jerusalem, over all Israel and Judah, for thirty-three years.
And David got together all the fighting-men of Israel to the number of thirty thousand;
And three of the thirty went down at the start of the grain-cutting, and they came to David at the strong place of Adullam; and the band of Philistines had taken up their position in the valley of Rephaim.
And Abishai, the brother of Joab, the son of Zeruiah, was chief of the thirty. He put to death three hundred with his spear, and he got for himself a name among the thirty.
Was he not the noblest of the thirty? so he was made their captain: but he was not equal to the first three
These were the acts of Benaiah, the son of Jehoiada, who had a great name among the thirty men of war.
He was honoured over the rest of the thirty, but he was not equal to the first three. And David put him over the fighting men who kept him safe.
Asahel, the brother of Joab, was one of the thirty; and Elhanan, the son of Dodai, of Beth-lehem,