Watch Eddie Murphy do the Billy Cosby impression he refused to do on 'SNL'

Earlier this week, comedian Norm MacDonald tweeted a great behind-the-scenes story about Saturday Night Live's 40th anniversary special and how Eddie Murphy refused to play Bill Cosby.

MacDonald explained how Murphy turned down the opportunity for big laughs in a "Jeopardy" sketch during Sunday's special:

Eddie Murphy does a perfect Cosby impression...

It's my job to talk him in to doing Jeopardy. We talk in his dressing room a good hour. When it's over, I'm convinced he'll do it. He doesn't. He knew the laughs would bring the house down. Eddie Murphy knows what will work on SNL better than any one. Eddie decides the laughs are not worth it. He will not kick a man when he is down. Eddie Murphy, I realize, is not like the rest of us. Eddie does not need the laughs. Eddie Murphy is the coolest, a rockstar even in a room with actual rockstars.

Instead, current SNL cast member Kenan Thompson played the embattled 77-year-old actor in a video daily double that was "taped" six months before the actor was plagued by allegations of rape and sexual assault.

Bill Cosby responded on Thursday, telling NBC News: "I am very appreciative of Eddie and I applaud his actions."

But before Cosby was thanking Eddie Murphy, he was reprimanding him back in the '80s when Murphy was just a young comic.

In the below clip from his 1987 standup special "Eddie Murphy: Raw," Murphy tells the story of how Cosby called to tell him to curb his cursing.

I'm a big fan of Billy Cosby. Never met the man but he called me up about a year ago and chastised me on the phone about being too dirty on the stage. It was real weird because I had never met him and he just thought he should call me up, because he was Bill, and tell me that that isn't what comedy is all about. I sat and listened to this man chastise me, and when Bill Cosby chastises you, you forget you're grown, you feel like one of the Cosby kids and s---t."

In his most Cosby-like voice, Murphy imitates the older comic, saying: "I would liiiike to talk to youuuu about some of the things that you do in the show."

Murphy proceeds to tell the story of their phone call while imitating Cosby. Watch the funny bit below, now more relevant than ever: