Jamieson, Fausset and Brown on Acts 25:7

7. the Jews ... from Jerusalem--clamorously, as at Jerusalem; see Ac 25:24.

many and grievous complaints against Paul--From his reply, and Festus' statement of the case before Agrippa, these charges seem to have been a jumble of political and religious matter which they were unable to substantiate, and vociferous cries that he was unfit to live. Paul's reply, not given in full, was probably little more than a challenge to prove any of their charges, whether political or religious.