Elon Musk’s not-so-friendly bid to buy OpenAI for $97.4 billion caught many in the tech world by surprise, but it’s just the latest shot in a yearslong battle between Musk and Sam Altman, who co-founded OpenAI together nearly 10 years ago.

The OpenAI CEO quickly rejected the deal on Musk’s X platform, saying, “no thank you but we will buy Twitter for $9.74 billion if you want.”

Sam Altman is leaving no room for doubt about his views on an Elon Musk-led bid to take control of OpenAI. In a letter to OpenAI staff Monday, the CEO put the words “bid” and “deal” in scare quotes and said the startup’s board has no interest in the offer.