كتب : Hatem Maher
Although several key players were rested like Ryan Giggs, Louis Saha and Paul Scholes, United managed to grab a satisfying win.
Scottish tactician Ferguson believes the Red Devils could not afford any slip-ups after the 1-1 draw with English champions Chelsea on Sunday.
"I think at this stage after dropping the two points on Sunday this was important - it's a good result for us," Ferguson told Sky Sports Network.
"With the game against Benfica next week and a match on Saturday we couldn't afford players coming in from the cold. We haven't changed many players, but this was the time to do it."
United will face Portuguese giants Benfica on Wednesday in a crucial UEFA Champions League clash at the Old Trafford.
Ferguson was delighted to see his defense halts any threat from Everton.
"Everton put you under pressure and (James) Beattie caused us a lot of problems but I thought we defended it quite well," he said.
"Our defensive record has to continue - that is the key to it this season."
United are in charge of the Premiership table on 38 points, three ahead of second-placed Chelsea, who edged Bolton 1-0.