Former President Barack Obama warned a group of mayors Thursday of the “biggest mistake” they could make during a crisis such as the ongoing COVID-19 coronavirus pandemic.

And though he never mentioned his successor by name, it sounded like a message for President Donald Trump.

“The biggest mistake any [of] us can make in these situations is to misinform, particularly when we’re requiring people to make sacrifices and take actions that might not be their natural inclination,” Obama said at a virtual meeting arranged by Bloomberg Philanthropies, according to a news release.

Trump has repeatedly misinformed the public about the nature of the coronavirus threat and the outbreaks across the United States.

In February, Trump said that the number of cases would go “down to close to zero” within a couple of days. He also repeatedly promised “millions” of tests for the infection when very few were available.

Obama said leaders in a crisis have to give the people the truth.

“Speak the truth. Speak it clearly. Speak it with compassion,” he said. “Speak it with empathy for what folks are going through.”

He also told the mayors to trust their experts.

“The more smart people you have around you, and the less embarrassed you are to ask questions, the better your response is going to be,” he said.

Obama has rarely mentioned Trump by name, but he’s offered up thinly veiled criticism of his successor several times over the course of the health crisis.

On Wednesday, he warned that the United States isn’t ready to reopen because the long-promised widespread testing still isn’t in place:

Social distancing bends the curve and relieves some pressure on our heroic medical professionals. But in order to shift off current policies, the key will be a robust system of testing and monitoring – something we have yet to put in place nationwide. https://t.co/evkTSrzReB — Barack Obama (@BarackObama) April 8, 2020

And last week, he warned of the consequences of science denial in a message that touched on both the pandemic and the climate crisis:

We've seen all too terribly the consequences of those who denied warnings of a pandemic. We can't afford any more consequences of climate denial. All of us, especially young people, have to demand better of our government at every level and vote this fall. https://t.co/K8Ucu7iVDK — Barack Obama (@BarackObama) March 31, 2020