Pharrell Williams sent President Trump a cease-and-desist letter Monday after the president’s campaign played the hit song “Happy” during a rally that took place just hours after the massacre at the Tree of Life Synagogue in Pittsburgh.

“On the day of the mass murder of 11 human beings at the hands of a deranged ‘nationalist,’ you played his song ‘Happy’ to a crowd at a political event in Indiana,” Williams’ attorney wrote in a letter obtained by the Hollywood Reporter.

“There was nothing ‘happy’ about the tragedy inflicted upon our country on Saturday and no permission was granted for your use of this song for this purpose.”

The letter continues to say that Trump does not have permission to use the song, and for him to continue to play it would be a violation of copyright laws.

Pharrell was responding to the carnage that took place Saturday when an anti-Semitic gunman opened fire on the Pittsburgh synagogue during prayers.

Despite the tragedy, Trump decided not to cancel a campaign-style rally in Indiana later that day, where the song was played.

During the rally, Trump joked that he had almost canceled the event because he had a “bad hair day.”