Nadal came into the tournament at London’s O2 Arena with a knee injury that forced him to withdraw from the Paris Masters two weeks ago.
The World No 1 was beaten by Belgian David Goffin in his opening game last night and immediately announced he would be quitting the event.
Speaking ahead of his match with Alexander Zverev this evening, Federer says his recovery has gone well since his win over Jack Sock on Sunday.
But he also wanted to send a message to Nadal, saying that he hopes he is fit from the start of 2018.
“It’s been easy (my recovery), had a day off yesterday,” Federer told Sky Sports.
“I played during the day time on Sunday so plenty of time there as well. I feel really good going into tonight.
“Of course it is a pity not seeing Rafa around anymore.
“We all hope he recovers quickly and well from that and comes back strong next year.”
Federer was beaten by tonight’s opponent Zverev in the final of the Rogers Cup in Montreal in August.
The Swiss legend admits he has been impressed by the rise of the 20-year-old German.
“The rise, the consistency now, the rise up the rankings,” Roger Federer said of Zverev.
“Winning the big titles, I think that has been something really difficult for any player on the tour.
“Breaking through the top four, top five guys, if you include Stan (Wawrinka) in that which he deserves.
“It’s hard to break through at the Masters, 1000s and the slams and he did that twice this year. So really credit to him.”