Piers Morgan sparks social media firestorm with Muhammad Ali tweet

>> RELATED STORY: Muhammad Ali dead at 74

Morgan first questioned why there was so much controversy over his tweet. He later sort of apologized, writing: "I'm sorry for 'saying inflammatory things for attention.' That's the last thing Muhammad Ali would have condoned."

>> Read the tweet here

Social media users were quick to slam Morgan:

Ali was well-known for his social activism but did say some controversial things — inside and outside the ring.

He once called his opponent Joe Frazier an "Uncle Tom" and said he worked "for the enemy." He also said Frazier was "so ugly, blind men go the other way."

Of course, Frazier was brash, too, saying, "If we were twins in the belly of our mama, I'd reach over and strangle him."

Ali also talked very candidly about race.

During a BBC interview, Ali said, "And I'm sure no intelligent white person watching this show ... want black boys and black girls marrying their white sons and daughters."

>> PHOTOS: Muhammad Ali through the years

And in 1967, when Ali famously refused to serve in the Vietnam War, he said: "Man, I ain't got no quarrel with those Viet Cong. No Viet Cong ever called me [expletive]."

As for Morgan, he's kind of known for stirring up controversy.

>> PHOTOS: Rumble in the Jungle: Nearly 42 years on

In April, he wrote an opinion piece of Beyonce´'s latest album, Lemonade, in the Daily Mail calling her a "militant activist" and saying she exploited mothers whose sons were shot by police.

>> Click here to watch the video from Newsy

This video includes clips from BBC and images from Getty Images, Dutch National Archives, Lorenzo9378 / CC BY SA 4.0 and Tyne & Wear Archives & Museums.