I just want to know. I heard it once and I want to know about it.
First and foremost, the person who says it has no right to say so, because we never know where we will end up and we cant decide for each other either. Only God can judge us.
So to answer your question, I seriously doubt that a believer would ever say it, because he would just be claiming that he will end up in hellfire. You will be judged in this life after how you behave. Islam is about everything in life, and it is your task to prove to God that you are among the good people. Saying things like this does not present you to God as the most sensible and kind person.
You have been giving so much knowledge and you are among the most intelligent creations, so we have to think for ourselves if our actions are right or wrong.
In the name of God, the Beneficent, the Merciful
Your question: Is saying “see you in Hell” haram?
[He is] Knower of the Ghaeeb [future and unseen] and the witnessed, the Grand, the Exalted. [13:9]
”Indeed, God [alone] has knowledge of the Hour and sends down the rain and knows what is in the wombs. And no soul perceives what it will earn tomorrow, and no soul perceives in what land it will die. Indeed, God is Knowing and Acquainted.” [31:34]
So, it haram for someone to say this, because also the Prophet said, “don’t speak without your knowledge.”
In conclusion, God doesn’t need you to prove to Him that you can do better, He has created us for a test only.
Did you think that We had created you in play (without any purpose) and that you would not be brought back to Us?” (Quran 23:115)
From above verse, we can conclude, we were indeed created for a purpose beyond that of simply play and enjoyment in this life. We have the purpose of life that we should know and have to live life according to that purpose. And the purpose of our existence is to worship Him alone without committing shirk or kufr, and also do good deeds.
It is haram to say to or about a person who is or died as a believer that he/she is (or will be) in Jahannam (Hell). As we only know that disbelievers will end up in hell:
Indeed, they who disbelieved among the People of the Scripture and the polytheists will be in the fire of Hell, abiding eternally therein. Those are the worst of creatures. (98:6)
So we can only conclude that a person is in Jahannam or hell if we clearly know that he/she died as a disbeliever!
According to Ahl al-Sunnah wa’l-Jamaa’ah, the basic principle is that the issue of who will go to Paradise and who will go to Hell is the matter of ‘aqeedah based on what is said in the Qur’aan and Sunnah, and there is no room for reasoning or ijtihaad in this matter.
Specific statements referring to people by name, stating that a particular person will be in Paradise or in Hell. This is not permissible except in cases where Allaah or His Messenger (peace and blessings of Allaah be upon him) have informed us of it. (Source: islamqa #731)
And as an interpretation of the hadith:
"None amongst you believes (truly) until he loves for his brother" - or he said "for his neighbour" - "that which he loves for himself."
(Sahih Muslim Version 1 and 2, Sahih al-Bukhari, Jami' at-Tirmidhi, Sunan ibn Majah and Sunan an-Nasa-i Versions 1, 2 and 3)
One could conclude that it is not permissible to whish or make du'a for a believer to throw him into hell