The former Manchester United manager wrote: "May I wish you a very special day on the occasion of your marriage".
Speaking at a press conference on Thursday, Mourinho insisted he would respect the demand of Ferguson's family for privacy but did note that they were feeling positive after three days.
Mata in a statement said, "This Saturday, all of us were overwhelmed by the news about Sir Alex Ferguson's health condition".
But, asked about the feeling among the squad, many of whom have written heartfelt messages on social media, and their hopes for a full recovery, Mourinho said: "We are very positive, we are confident".
"The procedure has gone very well but he needs a period of intensive care to aid his recovery. He is absolutely the boss", said Klopp after Liverpool's 1-0 defeat at Chelsea on Sunday. He has got all his family and friends around him, the support from all the players and staff at Manchester United and football around the world.
Ferguson retired from management in 2013 after nearly 27 years in charge of United, but has continued to regularly attend matches and participate in UEFA coaching initiatives.
Jose Mourinho: Sir Alex Ferguson's family feeling positive after successful operation
"That's what we try", said Mourinho, who added that Fellaini had a chance of playing at home to Watford in the final Premier League game.
"He is a great man". It's sad, but I know his character and I know he has that fight in him.
Sir Alex Ferguson worked as head coach of Manchester United from 1986 to 2013, winning this time a record number of titles with the club.
The haemorrhage, a bleed between the skull and surface of the brain, can cause speech loss and paralysis.
When asked if Ferguson's condition would have an impact on the team, Mourinho said: "No, I can only think that if there is any relation it is a positive relation".
"Hopefully they've found the bleed in the brain early enough and it doesn't affect the boss in any way", said Robson.
Iran foreign minister to meet counterpart in Moscow on May 14
President Donald Trump announced on Tuesday that the USA was withdrawing from the 2015 Iran nuclear deal. President Trump has instructed his administration to reinstate sanctions against Iran immediately.