Rapper/fight promoter 50 Cent continues to feud with WBC/WBA welterweight/junior middleweight champion Floyd Mayweather Jr. After already completing the ALS Ice Bucket Challenge earlier this week, the rapper sent a challenge to Mayweather.

50 Cent took to Instagram to call out his former friend and business associate, challenging him to read a full page of a Harry Potter book without messing up. If completed, the rap mogul intends to donate $750,000 to any charity of Mayweather’s choice.

"Floyd will you [accept] my ALS/ESL CHALLENGE: I will donate $750k to a charity of your choice, If you can read a full page out of a Harry Potter book out loud without starting and stopping or f***ing up. lmao," he wrote in the caption for the video.

The ALS Ice Bucket Challenge calls for nominated participants to pour ice water over their heads within 24 hours or donate $100 to help find a cure for ALS, a progressive degenerative nerve disease commonly known as Lou Gehrig's disease.  As of Thursday, more than $41 million has been raised by this year's campaign.

50 Cent's attack may have been a retaliation to an earlier interview that Mayweather conducted with MLive.com, where he took a swipe at rappers - without naming anyone directly. During the last few months, Mayweather has had issues with several rap talents - including 50 Cent, T.I. and Nelly.

"God has blessed me with an unbelievable talent, with fast feet, fast hands, unbelievable defense and a very, very sharp mind. So I'm thankful for that. Of course, hip-hop artists, they come and go. They come and go. But I'm still here," Mayweather said.