(NEXSTAR) — Tesla CEO Elon Musk has given employees of his electric vehicle company a choice: return to in-person work for 40 hours per week or resign, according to emails obtained by electric vehicle/tech news site Electrek.

In the emails, which Reuters says it’s also seen, Musk reportedly writes: “Anyone who wishes to do remote work must be in the office for a minimum (and I mean *minimum*) of 40 hours per week or depart Tesla… this is less than we ask of factory workers.” According to the documents, Musk reportedly writes that Tesla is working to create “the most exciting and meaningful products” in the world but that “this will not happen by phoning it in.”

CNBC reports Musk writes exceptions will be considered for “particularly exceptional contributors.”

Although he’s not yet responded to CNBC’s request for comment, Musk did respond to a screenshot of the reported leaked emails via Twitter. One user asked, “Hey Elon… any additional comment to people who think coming into work is an antiquated concept?”

Musk replied: “They should pretend to work somewhere else.”

In one of the emails, Musk reportedly explains he knows many companies aren’t requiring employees to return full-time or at all, but adds, “… but when was the last time they shipped a great new product?”

The requirement to return in-person comes after just over two years when remote work became the norm for a large portion of American workers. As pandemic conditions have waxed and waned, some major corporations have tightened remote work allowances, though few the size of Tesla have completely required it against the threat of resignation.

Corporations like Alphabet, Apple, Meta and Amazon have continued allowing some remote work for some employees. Attempting to retain employees has become more important for companies during “the Great Resignation,” during which a large portion of workers left jobs for a variety of reasons.

Recent research has pointed to workers preferring remote work – or at least the option of it – over in-office workdays, though it’s not yet known if employers will completely shift from the traditional model just yet.