According to Tesla and SpaceX CEO Elon Musk, a claim that he once scolded an employee for missing a company event to witness the birth of his child is “total BS.”

Musk is the subject of a new book, out next week, called Elon Musk: Tesla, SpaceX, and the Quest for a Fantastic Future. In it, tech reporter Ashlee Vance makes a pretty shocking allegation concerning Musk’s reaction to a man who chose to miss work during his child’s birth.

According to the book, Musk sent this email to the unidentified man:

That is no excuse. I am extremely disappointed. You need to figure out where your priorities are. We’re changing the world and changing history, and you either commit or you don’t.

Musk, who is always pretty quick to address any controversies, has responded on Twitter.

“I have never written or said this. Ashlee’s book was not independently fact-checked. Should be taken w a grain of salt,” he wrote. “It is total BS & hurtful to claim that I told a guy to miss his child’s birth just to attend a company meeting. I would never do that.”

@voxdotcom I have never written or said this. Ashlee's book was not independently fact-checked. Should be taken w a grain of salt.

— Elon Musk (@elonmusk) May 12, 2015

Of 22 Quotes from http://t.co/VA2KQ03NNR, 2 need correcting: 1. I strongly support pregnancy leave 2. I've never called myself a samurai

— Elon Musk (@elonmusk) May 12, 2015

It is total BS & hurtful to claim that I told a guy to miss his child's birth just to attend a company meeting. I would never do that.

— Elon Musk (@elonmusk) May 12, 2015

“My mentality is that of a samurai. I would rather commit seppuku than fail” is the other quote Musk disputes, by the way.