Republican presidential hopeful Ben Carson has chosen kindness in the face of rival Donald Trump's harsh words against him.

Armstrong Williams, Carson's campaign spokesman, told Reuters that the retired neurosurgeon wants prayers for Trump, who compared him to a child molester.

"When I spoke with Dr. Carson about this yesterday how we should respond, you know he was so sad about it," Williams said, as quoted by WND.com

"He said, 'Pray for him.' He feels sorry for him because he really likes Mr. Trump," he added.

Carson's spokesperson was reacting to earlier controversial statements made by Trump against his closest rival in the Republican presidential race.

In an interview on CNN's "Erin Burnett Out Front," Trump said that based on Carson's 1990 memoirs entitled "Gifted Hands," his fellow presidential aspirants seems to have "a pathological temper."

Trump then went on to compare Carson to a child molester, asserting that the retired neurosurgeon's temper was incurable.

"That's a big problem because you don't cure that. As an example: child molesting. You don't cure these people. You don't cure a child molester. There's no cure for it. Pathological, there's no cure for that," Trump said.

"I'm not bringing up anything that's not in his book. ... When he says he's pathological – and he says that in the book, I don't say that – and again, I'm not saying anything. I'm not saying anything other than pathological is a very serious disease," he added.

Carson nevertheless called Trump's comments as "completely gratuitous" and advised that the controversial business tycoon be taught about the correct meaning of the word "pathological."

"It's not the kind of dialogue that I would ever engage in. I'm hopeful that maybe [Trump's] advisers will help him understand the word 'pathological,' and recognise that it does not denote 'incurable'," Carson said.