On February 22, Trump said to his followers, as a protester was being led out of his rally--Trump said he loved the old days, when guys like that "would be carried out on a stretcher." Trump added, "I'd like to punch him in the face."
Then on March 9, one of Trump's followers did what Trump was wishing for and punched a protester in the face, as the protester was being escorted out. On March 13, Trump said he had instructed his people to look into helping the assailant with his legal fees.
Then again yesterday, on March 19, another Trump follower did the same thing and punched a protester in the face, as the protester was being escorted out. He also kicked the protester when he was down.
Now the Trump followers who committed these assaults are responsible for their own actions. But Trump is responsible for his own words. And in my opinion, Trump has shown a pattern of irresponsible comments and poor judgment.
So, there is no Proof, only innuendo. Got it.