Albert Barnes Commentary Acts 28:21

"And they said unto him, We neither received letters from Judaea concerning thee, nor did any of the brethren come hither and report or speak any harm of thee." — Acts 28:21 (ASV)

We neither received letters, etc. Why the Jews in Judea had not forwarded the accusation against Paul to their brothers at Rome, so that they might continue the prosecution before the emperor, is not known. It is probable that they regarded their cause as hopeless and chose to abandon the prosecution. Paul had been acquitted successively by Lysias, Felix, Festus, and Agrippa. Since they had not succeeded in procuring his condemnation before them, they saw no prospect of doing it at Rome and therefore chose not to press the prosecution any further.

Neither any of the brethren that came. Any of the Jews. There was very constant contact between Judea and Rome. However, it seems that the Jews who had come before Paul arrived had not mentioned his case in a way that would prejudice them against him.