Among the most interesting parts of Elon Musk’s testimony Tuesday in his lawsuit against OpenAI wasn’t the charity he claims was stolen from him (we all knew that was coming). It was about an old friend.

Musk testified that one of his core motivations for co-founding OpenAI was a falling out with Google’s Larry Page over AI safety — specifically, a conversation in which Musk raised the prospect of AI wiping out humanity and Page shrugged it off as “fine,” so long as AI itself survived. Page called Musk a “speciest” for being “pro human.” Musk called the attitude “insane.”

That’s mostly notable given how close the two once were. Fortune included them on its 2016 list of secretly best-friend business leaders; Musk was so comfortable with Page that he regularly crashed at his Palo Alto home. Page once told Charlie Rose that he’d rather give his money to Musk than to charity.

The friendship didn’t survive OpenAI. When Musk recruited Google AI star Ilya Sutskever to help launch the company in 2015, Page felt personally betrayed and cut off contact.

It’s a story Musk has told before — including to author Walter Isaacson for his bestselling biography of Musk — but Tuesday was the first time he said it under oath. Page hasn’t commented, and it’s worth remembering everything that Musk said was in service of a lawsuit. Still, as recently as 2023 he told tech podcaster Lex Fridman he wanted to patch things up: “We were friends for a very long time.”