Tens of thousands of people took to the streets this weekend to participate in the Families Belong Together march—a nationwide protest against the Trump administration’s “zero tolerance” immigration policy.

One of Saturday’s participants was Hamilton creator Lin-Manuel Miranda, who delivered a heartfelt performance at Lafayette Square in Washington, D.C.

“We're here today because there are a lot of parents who can't sing their kids,” Miranda told the crowd. “Well, I'm just going to sing a lullaby that I wrote, and this is for those parents. And we're not going to stop until they can sing them to their kids again."

The 38-year-old composer then began signing an a capella version of the Hamilton song “Dear Theodosia.” 

“You will come of age with our young nation/We’ll bleed and fight for you, we’ll make it right for you,” he sang on stage. “If we lay a strong enough foundation/We’ll pass it on to you, we’ll give the world to you/ And you’ll blow us all away/Someday, someday.”

Moments after he addressed the crowd of protestors, Miranda spoke to USA Today about the demonstration and Trump’s hypocritical policy that has separated more than 2,000 immigrant kids from their parents.

“[The policy] flies in the face of everything this administration purports to stand for: family values and keeping families together,” Miranda explained. “[…] You have to say, ‘What if this was me? What if this was me separated from you? Or you separated from your parents?’ You have to put yourself in the shoes of your fellow humans. And if you're unwilling to do that, that should say something to you.”

Miranda was one of many celebrities who marched in Saturday’s protests, including figures like Alicia Keys, Kerry Washington, Amy Schumer, John Legend, and Chrissy Teigen.