President Biden Made a Brief Cameo at Barack Obama's Big Party — Virtually: 'Happy Birthday, 44!'

Joe Biden was first in line to celebrate his pal Barack Obama's birthday.

On Saturday, the former President celebrated his 60th birthday with an intimate, outdoor gathering of about 200 family members and close friends on the grounds of his 29-acre Martha's Vineyard estate. The guest list included many of his famous friends including President Biden, Gayle King, Tom Hanks, Rita Wilson, and Steven Spielberg, John Legend, H.E.R., and Erykah Badu.

Though Biden was unable to attend in person, a source tells PEOPLE the President recorded a "heartfelt" video that was played at the party.

Biden's video tribute to his longtime friend was "heartfelt and focused on the bond between their families and the wonderful young women Obama's daughters and Biden's granddaughters had become," says the source.

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"The greatest gift of our time together is the bond between our families," Biden said. "Happy birthday, 44. Jill and I send you and Michelle our love. Look forward to seeing you soon."

The special moment also featured other videos from virtual guests and fellow world leaders like the Dalai Lama, and Justin Trudeau.

And for those guests who attended in person, they also had the chance to make a special tribute to Obama.

A childhood friend from Hawaii "gave a toast about what a friend he was even when the weight of the world was on his shoulders —and included some gentle ribbing," says the source.

Biden and the former President have famously developed a close bond over several years. Obama even joked they had a "bromance" during a speech in which he surprised then-Vice President Biden with the Medal of Freedom in 2017 before they left office.

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In the heartfelt speech, Obama described Biden as "the best vice president America has ever had," "a lion of American history" and a "brother." A choked-up Biden added, "Mr. President, you have crept into our heart, you and your whole family, and you occupy it." He continued, "I am indebted to you. I am indebted to you and your family."

The Obamas originally planned a COVID-safe outdoor party on the grounds of their Martha's Vineyard home, with required testing and other strict protocols for all guests. After the lengthy guest list and other details of the party were criticized, they scaled back the event for a more intimate gathering, with only friends and close family invited. They also cited the coronavirus pandemic and the rapidly spreading Delta variant for their decision.

"This outdoor event was planned months ago in accordance with all public health guidelines and with COVID safeguards in place," Hannah Hankins, a spokeswoman for the Obamas, told PEOPLE earlier. "Due to the new spread of the Delta variant over the past week, the President and Mrs. Obama have decided to significantly scale back the event to include only family and close friends."

Even without his pal Biden at his 60th birthday party, Obama still had "a great time" despite the celebration being scaled down amid the growing spread of the COVID-19 Delta variant.

"He never stopped smiling," another source close to the event told PEOPLE. "Literally, every time I saw him, he had the biggest smile."

The insider added that the birthday boy "danced all night."