John Stamos Honors Late Full House Costar Bob Saget's 66th Birthday: 'Miss You Madly'

Stephen Lovekin/Getty Images John Stamos and Bob Saget

John Stamos sent love to his late onscreen brother-in-law Bob Saget on the day the Full House star would have turned 66.

Stamos, 58, shared a smiling photo of him and Saget by the beach for the occasion. He quoted legendary actor Jack Lemmon at the top of the Instagram caption, writing, "Death ends a life, not a relationship."

He continued, "Happy Birthday Bobby. I miss you madly."

Saget's widow Kelly Rizzo replied to Stamos, "Truer words have never been spoken. Love you brother ❤️"

RELATED: Full House Cast Shares How They 'Pull Together as a Family' in Tough Moments: We 'Love Each Other'

Saget died unexpectedly on Jan. 9, and an autopsy later revealed he had died from head trauma consistent with some kind of fall.

Phillip Faraone/Getty Bob Saget

RELATED: John Stamos Delivered a Heartbreaking Tribute to Bob Saget at His Memorial — Read His Full Eulogy

Saget was laid to rest during a private ceremony in Los Angeles on Jan. 14, and Stamos published the remarks he made at his friend's funeral in the Los Angeles Times that same day.

"Bob was there for me like no other," he said in his speech.

"I'm not ready to accept that he's gone. I'm not going to say goodbye yet," he continued. "I imagine him out there, still on the road, doing what he loves with all his heart and humor. He's standing on stage, killing! Another two-hour set in front of a couple hundred of the luckiest people on the planet. ... Everyone here wants an encore with Bob."

ABC/Getty Bob Saget and John Stamos on Full House

RELATED: Caitlin McHugh Stamos Shares How Friend Bob Saget Inspired Her: 'He Was Always Helping People'

Stamos' wife, Caitlin McHugh Stamos, also spoke fondly of "America's Dad" last month.

"He was always helping people," she told PEOPLE.

"He was always connecting people," she continued. "Bob is so near and dear to our hearts."