Biden rages that 'you think I would ... forget the day my son died?' after special counsel report

President Joe Biden was not only furious in public about special counsel Robert Hur’s suggestion he struggled to remember when his son Beau died in his interview with investigators, his anger also flared in private, sources said Friday.

“You think I would f------ forget the day my son died?” they said Biden told a group of House Democrats on the sidelines of a caucus retreat in Virginia Thursday, according to sources familiar with his comments.

Not long after, speaking to reporters back at the White House, Biden mounted a fiery public defense to Hur's report that questioned his mental acuity and suggested his memory could be "hazy."

Speaking from the Diplomatic Reception Room, Biden addressed the issue, stating, "I know what the hell I'm doing."

On Thursday, Biden's memory was cited as one of the reasons the Justice Department wouldn't be filing charges against the president for his handling of classified documents. In Hur's report, he described Biden's mental fitness and ability to recall key moments of his political career, as sparse, apparently "hazy" and, in one interaction, claimed the president could not recall "even within several years" when his oldest son had died.

Biden took particular issue with that comment about the death of his son.

"How in the hell dare he raise that? Frankly, when I was asked the question, I thought to myself, it wasn't any of their damn business," Biden said.

"I don't need anyone to remind me when he passed away, or that he passed away," he continued.

When asked by one reporter if his memory has gotten worse over time, Biden insisted his memory is "fine."

"My memory -- take a look at what I've done since I've become president. None of you thought I could pass any of the things I got passed. How'd that happen?" he said.

In a back-and-forth with another journalist who brought up concerns over his age and mental acuity, and why Biden feels he is the one to beat former President Donald Trump in a general election for the presidency, Biden said he was the "most qualified person in this country to be President of the United States," and that it was to "finish the job" he started.

Biden said the special counsel's only role was whether or not to move forward with charges, but as for "any extraneous commentary, they don't know what they're talking about. It has no place in this report," he said.

"The bottom line is the matter is now closed, and we can continue what I've always focused on, my job of being President of the United States of America," he added.

But even as Biden tried to downplay concerns about his mental acuity, he had yet another misstep: referring to the President of Egypt as the President of Mexico.

"I think that, as you know, initially, the President of Mexico, el-Sisi, did not want to open up the gate to allow humanitarian material to get in," he said, referring to the border between Egypt and Gaza.

When Biden was asked by a reporter if there was anything he would do differently now that the investigation has concluded, the president said he wished he "had paid more attention to how the documents were being moved and where. I thought they were being moved to the archives. I thought all was being moved. That's what I thought.

"I take responsibility for not having seen exactly what my staff was doing," he added.

Biden did address the special counsel, laying out the differences between his handling of classified documents and the investigation into former President Donald Trump, praising the decision to include in the report information on why the former president was indicted and he wasn't. But he said it was "misleading" and "just plain wrong" that the report concludes that Biden willfully retained documents.

Spokespeople for both special counsel Hur and Attorney General Merrick Garland declined to comment on Biden's remarks when reached by ABC News.