Russell Simmons called out friend of 30-years Donald Trump in an open letter, in which he took the candidate to task over his recent proposal to have all Muslims banned from the U.S.

"Just cut it out, Donald," Simmons demanded in a letter published on Global Grind. Later, he compared Trump's crusade to a "one-man wrecking ball."

Simmons also detailed a friendship in which Trump has frequently endorsed his works, hosted his family and flown him across the country on his private aircrafts. Still, Simmons stressed he couldn't remain silent on an issue where he felt his friend was so wildly off the mark.

"I cannot disagree with them," Simmons said of a growing number of other Jewish and Muslim friends now comparing Trump's "rap" to Hitler.

The bombastic Trump has come under heavy criticism since his latest rant, and some are speculating it could ultimately hurt his standing as the current 2016 Republican presidential front-runner.

In light of it all, Simmons had a bit of advice for his longtime pal.

"Stop the bullsh*t," he wrote. "Stop fueling fires of hate. Don't feed into the rhetoric created by small-minded people."

Later, Simmons urged Trump not to "play to the cheap seats" and compromise what Simmons is convinced is truly in Trump's heart.

Since announcing his candidacy earlier this summer, Trump has seemingly made advocating for the controversial a staple of his campaign.

If elected, he previously pledged to deport some 11 million immigrants in less than two year's time and to build a massive wall along the Mexican border. Trump added he would handle all the mass deportations by building a "deportation force."

During one specific campaign speech, Trump also branded all Mexicans "rapists" and criminals, and argued the country has long been shipping all the worst of its undesirables across the U.S. border.