Imaam Al-Barbahaaree (d. 329H) said in his Sharh As-Sunnah:

“If you see a man criticizing the Companions of the Messenger of Allaah (saw), know that he is a person of wicked speech and desires, since the Messenger of Allaah said, ‘When my Companions are mentioned then withhold.‘”

[At-Tabaraanee from Ibn Mas’ood, and it is saheeh. See Silsilatul Ahaadeeth is Saheehah no. 34]