At a solemn memorial for the 30th anniversary of the Oklahoma City bombing, Bill Clinton decided to lighten the mood with a crack at Donald Trump—before delivering a pointed critique of modern political division.

“I’m old and I can’t run for anything anymore,” the 78-year-old former president told the crowd in downtown Oklahoma City on Saturday. “I’m almost as old as President Trump!”

The quip drew laughter from the crowd, but Clinton quickly pivoted to more serious matters, urging Americans to abandon grievance politics and embrace the so-called “Oklahoma Standard”—a post-tragedy display of kindness, respect, and unity.

“Everybody is arguing about whose resentments matter most,” he said. “If our lives are going to be dominated by the effort to dominate people we disagree with, we’re going to put the 250-year march toward a more perfect union at risk.”

Clinton was in office during the 1995 domestic terror attack, in which anti-government extremists Timothy McVeigh and Terry Nichols parked a truck filled with explosives outside the Alfred P. Murrah Federal Building, which was home to the America’s Kids Day Care Center. It detonated at 9 a.m. as employees were starting their day, killing 168 people, including 19 children.

“The nation’s eyes were there. The nation’s heart was broken there,” Clinton said in a separate reflection posted by the Clinton Foundation.

The speech was delivered at First Church, with the victims’ names read aloud and survivors in attendance. Clinton’s warning about the dangers of political polarization is hard to miss when confronted with the rubble of the Murrah building.

And yes, in case you’re wondering, Clinton is in fact younger than Trump. Despite public perception skewing the other way, Trump was born on June 14, 1946, while Clinton was born on August 19 of the same year, making the current president his senior by about two months.