In an open letter published on his website, music mogul Russell Simmons called Donald Trump an “amazing friend” for over 30 years, but then compared the GOP frontrunner to Adolf Hitler and pleaded with him to “stop fueling fires of hate.”

In the letter, Simmons described his roughly 30-year friendship with Trump. The prominent rap figure then unloaded on Trump, who called for a temporary moratorium on Muslim migration into the United States after last week’s terror attack in San Bernardino, California.

“Over 30 plus years you have been an amazing friend; endorsing my books, coming to my shows, flying me on your planes, your helicopters, and even allowing my family members and myself to stay in your house in Florida many times,” Simmons wrote. “So, it kinda pains me to know that my public statements about your candidacy have strained or ruined our friendship.”

Simmons added: “However, the fact is, what’s at stake is bigger than us.”

Citing his position as the Chairman of The Foundation for Ethnic Understanding, “whose sole mission is to fight bigotry of all kinds,” the hip-hop mogul then likened Trump to the Nazi dictator Adolf Hitler, who sent over six million Jews to their deaths during the Second World War:

My friends, both Muslims and Jews, are saying there are so many comparisons between your rap and Hitler’s, and I cannot disagree with them, Donald. You can’t possibly want your kids or your wife Melania (all of whom I know and respect) to live with that. You are a born leader, who is set to possibly win the nomination of your party, but don’t compromise what I know is in your heart to do it. You are a generous, kind man who has built a career on negotiating deals where everybody wins. Now, you seem like a one-man wrecking ball willing to destroy our nation’s foundation of freedom.

Simmons also called on Trump to “Stop the bulls—t,” and to “stop fueling fires of hate.”

“Don’t feed into the rhetoric created by small-minded people. You’re smarter and certainly more loving then you let on. The Republicans in power don’t like you any more than the Democrats in power, as they know you can’t be controlled, because you are your own man,” he wrote.

Simmons called Trump a “major embarrassment,” and added: “I know the cheap seats are easy to play to, but you can get them just by being the man I have known for nearly 30 years.”

He concluded, in part:

You are trying to be president of a country built on religious freedom; remember that the next time you discuss the beautiful followers of Islam. I would also like to remind you of one of my favorite quotes from the Holy Quran, “Love all men of good books equally.”

The minute you target one group or one religion or immigrants, you have failed.