Over the thirty, i.e. who came attended with thirty valiant Benjamites, and was their leader and commander.
Related Commentaries of 1 Chronicles 12:4
1 Chronicles 12:4
4 And Ismaiah the Gibeonite, a mighty man among the thirty, and over the thirty; and Jeremiah, and Jahaziel, and Johanan, and Josabad the Gederathite,