'Thirty' in the Bible

Among the Thirty were Joab's brother Asahel, Dodo's son Elhanan of Bethlehem,

Shiza the Reubenite's son Adina, a leader of the descendants of Reuben, along with thirty others with him,

Ishmaiah from Gibeon (who was one of the elite among the Thirty and in charge over them), Jeremiah, Jahaziel, Johanan, Jozabad from Gederah,

Then the Spirit came upon Amasai, leader of the Thirty, and he said, "David, we belong to you; we're with you, son of Jesse! Peace, peace to you, and peace to the one who helps you! For your deliverer is your God."

This was the same Benaiah who was one of the elite men of the Thirty and in command of the Thirty. His son Ammizabad was responsible for his division.

Then the king ordered Ebed-melech the Ethiopian: "Thirty men are at your disposal. Take them with you and bring up Jeremiah the prophet from the cistern before he dies."