From the New York Times,

“The 2024 election’s in full swing and yes, age is an issue,” Mr. Biden said in a roughly 10-minute speech. “I’m a grown man running against a 6-year-old.”

“Donald has had a few tough days lately. You might call it ‘stormy’ weather,”
...
“The New York Times issued a statement blasting me for ‘actively and effectively avoiding independent journalists,’” Mr. Biden said. “Hey, if that’s what it takes to get The New York Times to say I’m active and effective, I’m for it.”
...
“Did you hear what Donald said about the major Civil War battle?” Mr. Biden said. “Gettysburg. Wow. Trump’s speech was so embarrassing, the statue of Robert E. Lee surrendered again.”
...
“Age is the only thing we have in common,” Mr. Biden, 81, said of Mr. Trump, 77. “My vice president actually endorses me,”

On. A serious note,

“Focus on what’s actually at stake,” Mr. Biden said. “The stakes couldn’t be higher.”