Elon Musk says Tesla's AI Day has been pushed back to September

• Elon Musk says Tesla AI Day has been delayed until September 30.
• He tweeted that the electric car maker may have an "Optimus prototype" ready by then.

Elon Musk has pushed back Tesla's AI Day to September 30 from the planned date of August 19.

This will be the second time the electric car maker has held such an event.

Last year's AI Day aimed to lure top talent to the company, Musk said, but also provided insight into Tesla's progress toward fully autonomous cars.

This year's event should be very similar, as Musk said in May the purpose of AI Day is to convince great AI, software and chip talent to join Tesla.

The tech mogul said that the 2022 day could see "an Optimus prototype working by then."

Optimus, a human-sized robot Musk envisions will be able to perform common tasks like grocery shopping, was unveiled at the first AI Day.

Musk said in April on Tesla's first-quarter results call, according to CNBC: "I was surprised that people do not realize the magnitude of the Optimus robot program. Those who are insightful or who listen carefully will understand that Optimus ultimately will be worth more than the car business and worth more than full self-driving. That's my firm belief."

Tesla has been contacted for comment.

Musk recently issued an ultimatum to the company's staff, telling all workers to start coming into the office full-time and stop "phoning it in" or quit.

He said on the podcast Recode Decode in 2018 that his work at Tesla and SpaceX sometimes led him to sleep on the Tesla factory floor and work for more than 120 hours a week. He later reduced that to between 80 hours and 90 hours a week.

Musk believes that COVID-19 stay-at-home measures had "tricked people into thinking they don't actually need to work hard," he said in a tweet.

The Wall Street Journal reported that Musk no longer plans to fund his $44 billion takeover of Twitter with Tesla shares after its stock fell by about a third this year.