WASHINGTON — In a rare show of self-restraint from a man who often seems to lack it, President Donald Trump stayed off Twitter Thursday as former FBI Director James Comey testified in front of Congress.

His eldest son, Donald Trump Jr., had no such inclinations. The younger Trump had tweeted more than 80 times by 6:30 p.m. Thursday, defending his father and blasting Comey, the man his father fired last month.

Trump Jr. in particular seized on Comey’s assertion that he interpreted the president’s statement that he “hoped” the FBI would drop its probe into former National Security Adviser Michael Flynn as an instruction.

“Knowing my father for 39 years when he ‘orders or tells’ you to do something there is no ambiguity, you will know exactly what he means,” Trump Jr. wrote.

He also pointed to Comey’s revelation that he had asked a friend to pass along to the press memos he had written documenting his interactions with Trump. “Did I miss something or did Comey just say he asked a friend to leak information to the press?” asked Trump Jr. “Is this a joke?”

“That was fun,” Trump Jr. declared at the end of the hearing. He and his brother, Eric, now run their father’s business in New York.

The president, meanwhile, stayed silent, letting his personal attorney, Marc Kasowitz, do the talking. Kasowitz read a prepared statement to reporters in response to Comey’s testimony, in which he said the president had “never, in form or substance” directed Comey to stop investigating anyone.