Retired Harvard Law School professor Alan Dershowitz, an informal adviser to President Trump, said that the president should be more worried about prosecutors in New York than about the ongoing Russia probe led by special counsel Robert Mueller, the Washington Post reports.

Said Dershowitz: “I think he has constitutional defenses to the investigation being conducted by Mueller. But there are no constitutional defenses to what the Southern District is investigating. So, I think the Southern District is the greatest threat.”

He added: “Look, my advice to the president — I never gave it to him privately because I’m not his lawyer, but on television — is: Don’t fire, don’t pardon, don’t tweet and don’t testify. And if he listened to those four things, he’d be in less trouble than he is today.”