Ferguson, who won 13 Premier League titles at United, revealed he rejected Arsenal and Tottenham before taking on the Red Devils job in 1986.
The Scotsman had already achieved remarkable success at Aberdeen, winning the Premiership ahead of Celtic and Rangers, as well as beating Real Madrid on the way to a European trophy.
Speaking to Rangers and Scotland icon Ally McCoist on TNT Sports' YouTube channel, Ferguson said: "I turned down Arsenal and I turned down Wolverhampton Wanderers and I turned down Tottenham.
"I said (to Aberdeen chairman Dick Donald) that maybe it was time for me to leave, blah, blah, blah, and he said to me 'don’t talk like that'.
"You should go only to one club – Manchester United. I never budged until that came along. When it came along, I couldn’t get there quick enough.
"I have to say there was a lot of trepidation about it. Travelling down that morning, in the plane with Martin Edwards and the lawyer Maurice Watkins, I was asking a lot of questions and I wasn’t getting all the answers.
"Wee Gordon Strachan used to phone me quite a lot and I didn’t get a great picture through that. I knew all the players, world-class names in many ways.
"I was determined to install something I did at Aberdeen and St Mirren, and that was to produce young players."