'Thirty' in the Bible

David [was] thirty years old when he began to reign; he reigned forty years.

David again gathered all the chosen men in Israel, thirty thousand.

Then three of the thirty leaders went down and came to David {at the time of the harvest} to the cave of Adullam, while a group of [the] Philistines [were] camping in the valley of [the] Rephaim.

Now Abishai the brother of Joab the son of Zeruiah [was] himself the leader of the thirty. He [was] wielding his spear against three hundred slain and {gained a name} among the thirty.

Among the thirty, is it not that he [was] honored and became a commander for them? But he did not come up to the three

He [was] honored more than the thirty, but he did not come up to the three. David appointed him in charge of his bodyguard.

Among the thirty [were] Asahel the brother of Joab, Elhanan the son of Dodo of Bethlehem,