The music legend and former Beatles musician shared on Instagram a pic of the two at a party in the Hamptons in 2013.

"It seems that so many wonderful people are leaving this world, and now Jimmy Buffett is one of them," he wrote. "I've known Jimmy for some time and found him to be one of the kindest and most generous people."

Buffett, McCartney said, "had a most amazing lust for life and a beautiful sense of humour." He wrote, "When we swapped tales about the past his were so exotic and lush and involved sailing trips and surfing and so many exciting stories that it was hard for me to keep up with him. Right up to the last minute his eyes still twinkled with a humour that said, 'I love this world and I'm going to enjoy every minute of it.' So many of us will miss Jimmy and his tremendous personality. His love for us all, and for mankind as a whole."

McCartney continued, "Last, but not least, is his songwriting and vocal ability. If someone made an interesting remark he repeated it in his gorgeous Louisiana drawl and said, 'That's a good idea for a song.' Most times it didn't take too long for that song to appear. I was very happy to have played on one of his latest songs called 'My Gummy Just Kicked In.' We had a real fun session and he played me some of his new songs. One, in particular, I loved was the song, 'Bubbles Up.'"

The star later wrote, "So long, Jim. You are a very special man and friend and it was a great privilege to get to know you and love you. Bubbles up, my friend. Love, Paul."

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