David Letterman delivered a fiery rant against CBS and parent company Paramount for cancelling Stephen Colbert’s “Late Show,” calling the decision “gutless” and “pure cowardice” as he labeled his successor a martyr of the network.

On Thursday, CBS announced that it was cancelling the long running The Late Show with Stephen Colbert. The cancellation news came just days after Stephen Colbert, a critic of Donald Trump, called out Paramount, the parent company of CBS, over its $16 million settlement with the president.