The Manchester United manager insisted the Spaniard is "lucky" to have inherited a Chelsea team that sits third in the Barclays Premier League and will compete in the Club World Cup in Japan next month as European champions.
Ferguson feels the new interim manager at Stamford Bridge is benefiting from the achievements of Roberto di Matteo, who was sacked on Wednesday.
"Of course, Rafa Benitez is very lucky because on his CV in two weeks' time he could have two world club titles to his name and had nothing to do with the teams," Ferguson said ahead of United's match against Queens Park Rangers this afternoon.
"Jose Mourinho won the treble at Inter. Rafa took over and they won the world title [in 2010] without having to do anything. He had nothing to do with the construction of the teams.
"That's why I really feel disappointment for Roberto – he could have an FA Cup, Champions League and Club World Cup on his cv. It's a pity for him."
Ferguson and Benitez regularly indulged in mind games when the latter was in charge at Liverpool. In 2009, Benitez famously produced a hand-written list to back up his assertion that the Scot was never punished for verbally abusing match officials. Benitez also once said the fixture list always favoured United, claiming sarcastically that Ferguson organised it himself.
Despite the friction between the two Champions League-winning managers, Ferguson hopes Benitez enjoys victory in his first game in charge of Chelsea – against league leaders Manchester City at Stamford Bridge tomorrow.
"Benitez has been trying to get a job for a long time," Ferguson said. "I hope he is lucky on Sunday, too. It happens time and time again: when a new manager comes in, a team win their first few games. Sometimes you wonder if it encourages chairmen at football clubs to make changes."
Benitez, meanwhile, claimed it took him just one training session to see where Chelsea could improve. He was given just three days to pick his new team up for City's visit after Tuesday's defeat to Juventus sealed their Champions League departure at the end of the group stage.
The 52-year-old said: "We didn't talk about the Champions League or the next game but about little things I saw that we could improve a bit, and things they were doing well, which Roberto di Matteo was doing
"It's a good squad, a good team. If I'm here, it's because I think we can win with them. If we can improve by training hard, we will."
Roberto Mancini, the City manager, admitted he had warned his side to be wary of a Chelsea backlash in tomorrow's game. He said: "I am very sorry for Di Matteo because he won the Champions League, but this is the life of a manager.
"Usually, when a team changes a manager, the game afterwards is very difficult for the opponents. Chelsea were a good team with Di Matteo and will be a good team for Benitez. They have good players.
City were also eliminated from the Champions League in midweek after a 1-1 draw with Real Madrid but Mancini said it was a blow they were prepared for. "It was finished," he said. "It would have been difficult to go to the next stage. We made our mistakes before this game, not in this game."