Musk posted a meme of Bill Gates on Friday that appeared to mock his weight.

The meme had a photo of Gates with a pregnant man. Musk confirmed that the texts between the two billionaires were real after he posted it. The exchange showed that Musk had turned down a philanthropic opportunity with Gates as the CEO asked him if he had taken a short position in the stock.

The texts show Musk asking Gates if he still has a short position against the company.

Gates responded: "Sorry to say I haven't closed it out." He added: "I would like to discuss philanthropy possibilities."Musk appeared to shut down the potential partnership and wrote: "Sorry, but I cannot take your philanthropy on climate change seriously when you have a massive short position against Tesla, the company doing the most to solve climate change."

When Gates was asked about his views on billionaires focusing on space travel, he hit out at the founder of the company.

Space? Gates said in an interview with James Corden that they have a lot to do. His comments came a week after the first all-civilian mission by the company.