PHILADELPHIA – As Donald Trump addressed an Iowa event to complain that waterboarding was not allowed, the father of an American Muslim captain who was killed in 2004 taught him a lesson on patriotism, liberty and equal protection of law.

“We are honored to stand here as the parents of Capt. Humayun Khan,” the elder Khizr Khan said at the Democratic convention, “and as patriotic American Muslims with undivided loyalty to our country,” The Washington Post reported.

Humayun was a captain in the US Army. He was killed in Iraq in 2004 when a vehicle packed with explosives approached his camp, instructing his men to seek cover as he ran toward it.

The car exploded, killing Khan instantly. He was awarded the Bronze Star posthumously.

Trump called for Muslims to be banned from entering the US, making it a centrepiece of his candidacy.

Last week, in an interview with 60 Minutes, Trump called for “vetting” people hailing from countries with a history of “terror”.

Speaking at the Democratic National Convention on Thursday, July 28, the father of the deceased Muslim soldier took Trump down.

“If it was up to Donald Trump, [Humayun] never would have been in America,” Khan said.

“Donald Trump consistently smears the character of Muslims. He disrespects other minorities, women, judges, even his own party leadership. He vows to build walls and ban us from this country.

“Donald Trump, you are asking Americans to trust you with our future. Let me ask you: Have you even read the US Constitution? I will gladly lend you my copy,” he said to a standing ovation.

He pulled a copy of the Constitution from his pocket. “In this document, look for the words ‘liberty’ and ‘equal protection of law.’ ”

“Have you ever been to Arlington Cemetery?” Khan said. “Go look at the graves of the brave patriots who died defending America — you will see all faiths, genders, and ethnicities.

“You have sacrificed nothing. And no one.”