I'll admit straight up when I fire someone I am usually so relieved if they leave peacefully that I don't just say they worked for me, I will usually even give a semi positive review of them. Not a glowing praise or anything of the sort, but usually a review saying how they're a good team player, they get along well with others, and other aspects highlighting mostly soft skills.

As I've indicated many times on here... most incompetent people are genuinely good, nice people who get along well with others and it's devastating to have to fire them, so when I do fire them it can soften the blow for them to leave some good words, give some positive feedback which allows them to leave on good terms.