The Wall Street Journal is reporting that Tucker Carlson’s firing from Fox News came after he used vulgar language to describe a network executive.

Carlson described a senior Fox News executive as a C-word in a text message obtained by lawyers as part of a defamation lawsuit between the network and Dominion Voting Systems.

Other messages in which he called the Donald Trump adviser and attorney Sidney Powell attorney a C-word and a “bitch” were made public as part of the lawsuit.

Carlson’s internal messages were among the most embarrassing for Fox, as he said he “passionately hated” Trump and called for a colleague to be fired for accurately fact-checking claims about voting machines.