United went three seasons without winning the Premiership title, up to last May.
Ferdinand told The Sun: “The team we had when I first came here in 2002 was on a downward slope in terms of age. The manager knew he had to do some reshuffling — and has done it admirably.
“To be part of it during the transition was difficult.
“We still wanted to be winning games but were drawing and losing too many. We weren’t contenders any more.
“Yet the manager trusted his judgment, as did his management team and the board. He always had faith in what he was doing and we stuck by him.
“Last year we showed what he was working towards. We had a great resilience and showed how the team has grown.”
He declared: “I cannot imagine life at Manchester United without Sir Alex.
“He brought me here and I just hope he does not retire while I’m still about.
“He still has a great passion, desire and pride, is the lifeline of the club and has been since he arrived.
“I cannot think what the club would be without him.”
