Mourinho was sacked by United on Tuesday, December 18, after guiding the side to one of their poorest starts in years.
The club made public departure of the tactician two days after losing 3-1 to Liverpool in a Premier League clash at Anfield.
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Mourinho tutored the Red Devils for more than two years, in a reign that was punctuated with controversial moments.
The former Chelsea boss is believed to have fallen out with key squad members, including Paul Pogba, Anthony Martial, Luke Shaw and Eric Bailly.
However, unlike a section of the players, Bailly has since sent Mourinho a class message, thanking the Portuguese for his time at United.
In an Instagram post shared on the defender's account, Bailly appreciated Mourinho for giving him the chance to play for Manchester United, despite differences between the pair.
"Whatever they may say, I will always be thankful to the person who gave me the chance to make my debut at Old Trafford," he submitted.
"Thank you for what you have taught me. Good luck, coach," he added.
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Mourinho signed Bailly in 2016 from La Liga side, Villareal for a reported fee of £30 million.
He played a central role in the ex-manager's heart of defense, including Mourinho's final game against Liverpool.