The father of a Muslim U.S. soldier killed in Iraq blasted Donald Trump Saturday for suggesting his wife was "not allowed" to speak during a powerful speech at this week's Democratic National Convention.

"Running for president is not an entitlement to disrespect [a] Gold Star family and Gold Star mother, not realizing her pain,"Khizr Khan said in an interview on ABC News Saturday.

"Shame on him! Shame on his family!" Khan said. "He is not worthy of our comments. He has no decency. He is void of decency. He has a dark heart," Khan said.

In an interview to be broadcast Sunday on ABC’s "This Week,” Trump implied that Khan’s wife, Ghazala Khan, "wasn't allowed to have anything to say" when she stood next to her husband at the convention.

The Khans’ son, U.S. Army Capt. Humayun Khan, was killed by a car bomb in 2004 while guarding the gates of his base in Iraq, saving the lives of his fellow soldiers and civilians.

At the convention, Khizr Khan questioned whether Trump had read the U.S. constitution, and said Trump has "sacrificed nothing and no one." Trump has proposed a temporary ban on Muslims from entering the U.S.

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Ghazala Khan on Friday night told MSNBC's Lawrence O'Donnell that she was anxious during her husband's speech, knowing her son's photo would appear behind her. She also spoke on ABC News Saturday.

"Sacrifice — I don’t think he knows the meaning of the sacrifice, meaning of the word,” Ghazala Khan told ABC News. "Because when I was standing there all America felt my pain, without saying a single word. Everybody felt that pain, but I don’t know how he missed that."

Related: Khizr Khan Pleads to McConnell, Ryan to Take Moral Stand

In the interview with ABC News' George Stephanopoulos that will be broadcast Sunday, Trump questioned why Ghazala Khan stood silent during her husband’s speech. It was the first time Trump had commented at length about the speech, which was seen by some as one of the more powerful moments of the convention and a stinging rebuke to Trump.

"If you look at his wife, she was standing there. She had nothing to say. She probably, maybe she wasn't allowed to have anything to say. You tell me, but plenty of people have written that she was extremely quiet, and it looked like she had nothing to say," Trump said.

At another point in the interview, Trump was asked about sacrifice and said: "I think I've made a lot of sacrifices. I work very, very hard. I've created thousands and thousands of jobs, tens of thousands of jobs, built great structures. I've had tremendous success. I think I've done a lot."

The Trump campaign, apparently in damage control, released a statement Saturday night in which Trump praised Capt. Humayun Khan’s sacrifice.

"Captain Humayun Khan was a hero to our country and we should honor all who have made the ultimate sacrifice to keep our country safe," Trump said in the statement.

"The real problem here are the radical Islamic terrorists who killed him, and the efforts of these radicals to enter our country to do us further harm. Given the state of the world today, we have to know everything about those looking to enter our country, and given the state of chaos in some of these countries, that is impossible," Trump said.

Captain Khan, killed 12 years ago, was a hero, but this is about RADICAL ISLAMIC TERROR and the weakness of our "leaders" to eradicate it! — Donald J. Trump (@realDonaldTrump) July 31, 2016

But Trump also bristled at the DNC speech in the statement, and said Khizr Khansaid "many inaccurate things."

"While I feel deeply for the loss of his son, Mr. Khan who has never met me, has no right to stand in front of millions of people and claim I have never read the Constitution, (which is false) and say many other inaccurate things," Trump said.

Khan did not say Trump had never read the Constitution. He said, "Donald Trump, you're asking Americans to trust you with their future. Let me ask you: Have you even read the United States Constitution? I will gladly lend you my copy."

Former Republican presidential candidate and current Ohio Gov. John Kasich Tweeted Saturday: "There's only one way to talk about Gold Star parents: with honor and respect. Capt. Khan is a hero. Together, we should pray for his family."

There's only one way to talk about Gold Star parents: with honor and respect. Capt. Khan is a hero. Together, we should pray for his family. — John Kasich (@JohnKasich) July 31, 2016

Hillary Clinton earlier Saturday released a statement supporting the Khans, and saying "I was very moved to see Ghazala Khan stand bravely and with dignity in support of her son."

Bill Clinton at a campaign event in Youngstown, Ohio, Saturday praised the Khans and their son in an interview with NBC's Andrea Mitchell. "That man proved that we are right in America not to have a religious test for who can be part of our country. And his father was powerful and it must have taken everything that mother had to stand up there and go through it," Bill Clinton said.