(NewsNation Now) — President Joe Biden called for healing and reflection in a nearly 7-minute video commemorating the 9/11 attacks Friday night ahead of a litany of observances planned for Saturday.

“Unity is what makes us who we are. America at its best. To me, that’s the central lesson of September 11. At our most vulnerable in the push and pull of all that makes us human, in the battle for the soul of America unity is our greatest strength.”

Biden’s message Friday spoke mostly to victim’s families. He praised them for persevering through devastating grief. He also hailed the first responders.

“We honor all those who risked and gave their lives and the minutes hours, months and years afterwards. The firefighters, police officers EMTs and construction workers and doctors and nurses, faith leaders, service members veterans and all of the everyday people gave their all to rescue, recover and rebuild.

“But it’s so hard.”

The president will commemorate the solemn anniversary on Saturday by paying his respects at the trio of sites where the hijacked planes struck, puncturing the United States’ air of invincibility and resulting in the deaths of 3,000 Americans.

First will be a stop in New York City, where the twin towers of the World Trade Center were toppled as a horrified world watched on television. Then, a field near Shanksville, Pennsylvania, where a plane fell from the sky after heroic passengers fought terrorists to prevent it from reaching its Washington destination. And finally, the Pentagon, where the world’s mightiest military suffered an unthinkable blow to its very home.

Biden’s task, like his predecessors before him, will be to mark the moment with a mix of grief and resolve. A man who has suffered immense personal tragedy, Biden speaks of loss with power and eloquence, and he has repeatedly addressed the grief caused by the COVID-19 pandemic that has claimed more than 600,000 lives across the country.

“For Biden, it’s a moment for people to see him not as Democratic president, but as president of the United States of America,” said Robert Gibbs, who served as President Barack Obama’s press secretary.

“One year after, it still felt like it was immediately after the attack, the nation was still gripped by its consequences,” said Ari Fleischer, President George W Bush’s press secretary. He said that all presidents must offer messages of “comfort and reassurance” but also strength.

This anniversary happens in the shadow of a chaotic, deadly withdrawal from Afghanistan that left some Gold Star families and veterans wondering if the effort was worth it.

The resulting changes to security at airports and government institutions remain to this day.

“There are lessons to be learned because there are terrorists who would love to create a September 12th if the U.S. ever lets down its guard,” said Fleischer.