Every person’s environment has “nectar”. One should take the “nectar” and ignore the “thorns” like the honeybee. There is a simple criterion: when you do not become happy with people praising you and do not feel bad for being criticised, you are gaining spirituality.
Criticism is super blessing. Criticism tells you how to decondition yourself.
When you look into the mirror, you may see a spot on your face. You will thank the mirror because it revealed your spots. You immediately clean your face. The same is true of your critic. You must thank him because he tells you your weakness.
Hazarat Umar said: Copy arabic text (Tafsir al-Razi, v. 32, p. 282) He raised his critic to a very high level in his eyes because he showed him his shortcomings. As you thank the mirror and accept its critique, you must also do this in other matters.
There is an Arabic saying: One who gives you advice is better than one who praises you: ناصحك خير ممن هو مادحك. If a person wrongly criticizes you, it is his problem. We don't need to go after him.
If a person's critique is right, you must accept it. If it is false critique, for example, if he does character assassination, then you must avoid him. Take what is pure and leave what is dirty. Criticism is very important. The presence of criticism in a society or an organization is a very healthy sign.