Obama took a veiled shot at Trump's Twitter habit during a $400,000 appearance
"For starters, by not having a Twitter account," Obama said, according to the New York Post.
The comment was an apparent shot at President Donald Trump, whose frequent use of Twitter to launch attacks on his critics has drawn considerable attention.
Obama has notably not criticized his successor publicly since Trump took office in January.
Obama was reportedly paid $400,000 to appear at the 90-minute History Channel event, called a "History Makers lunch," during which he was interviewed by presidential historian Doris Kearns Goodwin.
Goodwin reportedly offered a historical take on presidential frustration, noting that Abraham Lincoln would write angry letters and, instead of sending them, file them away in a desk drawer.
The historian, who has interviewed Obama before, also asked the former president what he missed most about his time in the White House, to which Obama responded: sitting on the Truman Balcony on summer nights and taking in the view of the Washington Monument and Lincoln Memorial.