'Thirty' in the Bible

David was thirty years old when he became king, and he reigned forty years.

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

Then three of the thirty chief men went down and came to David in the harvest time to the cave of Adullam, while the troop of the Philistines was camping in the valley of Rephaim.

Abishai, the brother of Joab, the son of Zeruiah, was chief of the thirty. And he swung his spear against three hundred and killed them, and had a name as well as the three.

He was most honored of the thirty, therefore he became their commander; however, he did not attain to the three.

He was honored among the thirty, but he did not attain to the three. And David appointed him over his guard.

Asahel the brother of Joab was among the thirty; Elhanan the son of Dodo of Bethlehem,