"I don't care who you have in there; keep it down" -- Neighbor with an early shift
They already had a drummer in jazz genius (and Davis' bandmate) Tony Williams, so all they needed was a bassist. Hendrix proposed asking Paul McCartney to join them -- because if you're Jimi Hendrix, you have the power to snap your fingers and summon a Beatle like he's a genie in a submarine-shaped bottle.
In order to get McCartney on board, the trio sent out a telegram asking Paul if he might be gracious enough to put in an appearance in the recording studio.
They signed it "Peace, Jimi Hendrix Miles Davis Tony Williams" because why not.
Hendrix and Davis received a swift answer from The Beatles' personal assistant regretfully informing the duo that Paul was on vacation in Scotland. And that was it. They never heard from McCartney or anyone in his camp after that. Though Hendrix and Davis were still serious about logging some studio time, the project hit a lull after McCartney's snub. Hendrix died not soon after in September of 1970, forever robbing the world of a bunch of awkward looks between him and McCartney as the latter tried to pretend he never got his message at some red carpet event.