Tesla CEO Elon Musk sent out an email to company employees asking them to return to the office or leave the company.

Musk wrote, “Everyone at Tesla is required to spend a minimum of 40 hours in the office per week. If you don’t show up, we will assume you have resigned,” in an email sent on Tuesday night.

“The more senior you are, the more visible must be your presence,” Musk went on. “That is why I lived in the factory so much — so that those on the line could see me working alongside them. If I had not done that, Tesla would long ago have gone bankrupt.”

Tesla did not respond to a request for comment.

Many major tech firms in Silicon Valley have forgone requiring workers to show up to the office as employees resisted such mandates, and COVID cases surged in California. Although Tesla has moved to Austin, Texas, it still maintains its engineering headquarters and a factory in the Bay area.

“There are of course companies that don’t require this, but when was the last time they shipped a great new product? It’s been a while,” Musk continued.

“Tesla has and will create and actually manufacture the most exciting and meaningful products of any company on Earth. This will not happen by phoning it in.”

Tesla employees complained on the anonymous App Blind, which requires a company email on signup to confirm employment at the company they write about. “If there’s a mass exodus, how would Tesla finish projects? I don’t think investors would be happy about that,” one Tesla employee posted.

“Waiting for him to backpedal real quick,” another worker said.

Stephen Knight, executive director at Worksafe, a California-based workers advocacy group, wrote in an statement, “Employers including the state government are finding that mandating a return of all employees is a recipe for outbreaks. “Unfortunately Tesla’s disregard for worker safety is well documented, including their flouting of the county public health department at the start of the pandemic.”

In May 2020, when Musk reopened a Tesla factory in Fremont, California, Tesla reported 440 cases at the factory from May to December 2020. Meanwhile, SpaceX reported 132 COVID-19 cases at its headquarters.

Musk has diminished the dangers of COVID-19, saying “the coronavirus panic is dumb” and noting that children were “essentially immune.” He has had COVID-19 twice.