Buffett and Munger both grew up in Omaha, Nebraska, (hence Buffett's nickname, the "Oracle of Omaha") where they both worked at a grocery store owned by Buffett's grandfather, though they did not work there at the same time. They didn't get to know one another until a mutual acquaintance brought them together , when Munger was 35 and Buffett was 29. The two men had dinner together and quickly bonded.

Munger, who is Buffett's right-hand man in his role as the vice chairman of Berkshire Hathaway (Buffett is the chairman and CEO), has known the billionaire investor since 1959. The two men have worked together since 1978, when Munger left his own investment practice to join Berkshire Hathaway. More than a decade earlier, Buffett had convinced Munger to leave his law practice (Munger co-founded the law firm Munger, Tolles & Olson), because "it didn't use his full talents," Buffett told CNBC.

"We've never had an argument in the entire time we've known each other, which is almost 60 years," Buffett said of Munger in an interview with CNBC's "Squawk Box" in 2018.

Warren Buffett has been working with his long-time friend and business partner, Charlie Munger, for over 40 years. The two men have experienced unparalleled success together, building an investment business with more than $736 billion in assets. And, perhaps even more impressively, they've never had one argument.

Charles Munger, vice chairman of Berkshire Hathaway Inc., left, and Warren Buffett, chairman of Berkshire Hathaway Inc., attend a BYD Co. press event in China, on Monday, Sept. 27, 2010.

"We went to dinner and in five minutes, Charlie was rolling on the floor laughing at his own jokes — and I do the same thing," Buffett, who is now 88, told CNBC in 2018. "We knew we were sort of made for each other," Buffett added about Munger, who is now 95.

Those feelings turned out to be correct, as the two men have stayed close friends ever since. And, even after being friends for about 60 years, and working together for more than 40 years, Buffett still says he can "always learn something" from spending time with Munger.

That could explain why the two friends and partners have never had an argument — though that doesn't mean they agree on everything. "We are strong-minded, we disagree on a few things," Buffett said. At the same time, though, Buffett added: "We agree on most things and we have a great time together."

The fact that Buffett and Munger enjoy each other's company seems to have strengthened their working relationship, and that's also likely why they don't argue.

"We've got an extremely good partnership and business is more fun — just as life is more fun — with a good personal partner and to have great business partner," Buffett said. "You know it's just — we've accomplished more but we've also had way more fun."

Their strong bond is also a result of mutual respect. Munger told CNBC in 2016 that he and Buffett "don't agree totally on everything, and yet we're quite respectful of one another."

There are "not too many people I listen to," Buffett told CNBC. "But, Charlie, he's given me a lot of good advice over time. And, I may hate to take it to a certain degree, but sometimes — but my decisions have been better. I've lived a better life because of Charlie."

Clearly, their relationship has been a successful one, judging by Berkshire Hathaway's amazing track record of outperforming the overall stock market every year going back to the 1960s. As a result of their success together, Munger is now worth about $1.7 billion, according to a recent estimate by Forbes, while Buffett has a net worth of more than $84 billion, making him the third-wealthiest person in the world.

Don't Miss:

Warren Buffett remembers first meeting Charlie Munger

The life-changing career advice that Warren Buffett gave Charlie Munger

Like this story? Subscribe to CNBC Make It on YouTube!