Becks spent a decade at Old Trafford before being sold to Real Madrid for £25million shortly after Fergie accidentally kicked a boot at him, causing a cut that needed two stitches over his eye.
The LA Galaxy star said: "It's been amazing. But that's what happens when you have stability, and a man that is so passionate and hungry, who has the love for one club that he has.
"That loyalty and respect for one club is unbelievable and it's not something you see these days.
"It says a lot about United as a club and the manager."
Beckham added: "It's 50/50 with my parents — that's how highly I regard the boss.
"My parents were the ones who brought me up and helped get me to a certain level in my career, and the manager is the one who took me to a whole different level.
"He's the sole reason why I was successful. He gave us everything we needed to become the players and the men that we are today."