NETFLIX Malcolm X (left) and Muhammad Ali
But from the moment the Civil Rights leader met the boxer in 1962, he was absolutely fascinated by the young fighter, who was still going by Cassius Clay at the time.
"I think what he admired in Muhammad Ali was his wisdom," Ilyasah Shabazz, Malcolm X's 59-year-old daughter, tells PEOPLE. Shabazz is the third of six children he had with his wife Betty Shabazz. "They had so much in common: seeking identity and purpose and also sharing a great sense of humor."
Their deep bond, followed by a tragic falling out, is documented in the new Netflix documentary Blood Brothers: Malcolm X and Muhammad Ali directed by Marcus A. Clarke.
At the time of their 1962 meeting, Ali was learning more about Islam, and was drawn to Malcolm X, the charismatic top lieutenant and spokesperson for the Nation of Islam, the religious and political organization founded by Elijah Muhammad in 1930.
Ali's eldest daughter Maryum, 53, says, "I think my dad admired Malcolm's desire to constantly learn and grow intellectually and spiritually. And I think he learned from that because my father, he was like that himself. Malcolm was an example to always evolve. He saw how Malcolm was an intellectual and a critical thinker."
NETFLIX Malcolm X (left center) with Muhammad Ali (right center)
The two forged an immediate friendship, and in January 1964, as Ali was training in Miami to fight Sonny Liston for the heavyweight championship, Malcolm brought his wife and three children to visit and give him a confidence boost.
Meanwhile, those around Ali were concerned about the boxer being associated with the Nation of Islam. One promoter threatened to cancel the match. Eventually, another promoter intervened and the event remained on schedule, while Malcolm agreed to leave town until the match. But the visit boosted Ali's confidence, and on Feb. 25, 1964, he defeated the heavily-favored Liston.
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That night, the new champ celebrated with Malcolm, NFL running back Jim Brown, and singer Sam Cook. That meeting was fictionalized last year in Regina King's acclaimed film One Night in Miami.
Two days after the fight Ali announced he was Muslim. By then, the relationship between Malcolm X and Muslim Brotherhood NOI leader Muhammad had begun to fracture over opposing views on issues including police brutality and President Kennedy's assassination. Muhammad was also envious of the growing popularity and impact Malcolm was having.
NETFLIX Muhammad Ali (left) and Malcolm X (right)
"It was Malcolm who was responsible for the exponential growth of Islam in the United States," says Shabazz. "In 1952, he established four temples. And by 1955, there were 15 temples. And by 1959, there were 50 temples. My father made a significant contribution to ensure this organization could inspire and uplift and rehabilitate all these descendants of slavery who had been miseducated about their identity and the psychological warfare that was played on them, the systematic psychological warfare."
In addition, the FBI and the CIA were constantly spying on the organization and had even infiltrated it. "J. Edgar Hoover was skilled at infiltrating and subverting Black power movements," says Ali. "So you did have people in there helping the divisiveness."
On March 6, 1964, Muhammad revealed in a radio address that he was giving Cassius Clay the Muslim name Muhammad Ali. At that point, the leader reminded his prized follower he wasn't to have anything to do with Malcolm X.
"I believe the fact of the matter is my father was being poisoned with lies told about Malcolm," says Ali's daughter Maryum.
The public learned about their shattered friendship that spring when both men independently traveled to Ghana and ran into each other outside a hotel. When the minister tried to warmly greet his former pupil, Ali said, "You left the Honorable Elijah Muhammad – that was the wrong thing to do, Brother Malcolm," before turning away.
After leaving the Nation of Islam, Malcolm renounced several of Muhammad's teachings, and, in one poignant interview, revealed that the organization's leader had fathered several children out of wedlock from affairs with the young female staff that surrounded him.
It enraged members, and Malcolm began receiving regular death threats. On Feb. 21, 1965, the iconic leader was gunned down as he was beginning a speech at New York's Audubon Ballroom by three men who claimed to be members of the Nation of Islam, though there are doubts as to their true affiliation.
Ali, meanwhile, left the group in 1975, turning to Sunni Islam. After that, he reached out to Betty and her children, and the two families have remained close ever since.
Maryum says, "I was happy, happy, happy that my father was connected with Malcolm's daughters and it was always like, 'Wow, this is awesome.' And it was full circle just to see my dad own up to his mistakes and look back in retrospect. It's the power of Malcolm and how he just sacrificed everything. And to have his daughters connected to our family, I was really, really happy."
Ali called rejecting his friend his biggest mistake. He wrote in his book, The Soul of a Butterfly, "Turning my back on Malcolm was one of the mistakes that I regret most in my life. I wish I'd been able to tell Malcolm I was sorry, that he was right about so many things."
"I never really knew that there was any rift between Muhammad Ali and Malcolm X growing up," says Shabazz. "We were so young when my father was killed. We were so young when my father had a relationship with Muhammad Ali. My oldest sister (Attallah, 62) was six years old so she has a very clear and vivid memory, I would imagine, of visiting Muhammad Ali when he fought against Sonny."
"I just remember my sisters and I, we would be watching these fights and we were all like girls, we were squeamish, we would scream whenever he would get hit," she says. "We loved him so much. And in between every round, we would run to the Quran and maybe say a quick prayer and come back just to make sure that he won. So we weren't aware of any rift, we just loved him always. And I remember when I first even met Maryum, how excited I was, at the time I think most people called her May May. And meeting some of her sisters, we had this affinity, this connection with them."
She continues, "I remember one time being at some event, looking up at him and asking him did he love my father. And he said he loved my father with all his heart."
Blood Brothers: Malcolm X and Muhammad Ali is now streaming on Netflix.