How Do You Sleep?

The feud between Paul McCartney and John Lennon began during the recordings of the White Album. Yoko Ono first appeared at the studio during the recording sessions. Wives and girlfriends had previously never been allowed in the studio before, and the other Beatles were furious Lennon would bring Ono onto the set. Tension continued through the remaining years of the Beatles. Lennon said, "I always thought there was this underlying thing in Paul's 'Get Back.' When we were in the studio recording it, every time he sang the line, 'Get back to where you once belonged,' he'd look at Yoko." After the band broke up, tensions were even greater. During Lennon's solo career, he wrote a song called "How Do You Sleep?" about McCartney. It made references to him dying creatively. McCartney was hurt by this, especially when he learned of who was working on it: many of McCartney's friends, including former Beatle George Harrison.
http://www.youtube.com/watch?v=GK7CLXHSr1M