Bukhari

Hadith Commentary:
(1)
Imam Bukhari rahimahullah has mentioned this hadith in detail at another place, where the Messenger of Allah sallallahu alayhi wa sallam said:
"Among those before you, a man was wounded and became distressed. He took a knife and cut his wounded hand. His blood did not stop flowing until he died. Upon this, Allah the Exalted said: 'My servant has hastened before Me, so I have made Paradise forbidden for him.'" (Sahih al-Bukhari, Ahadith al-Anbiya, Hadith: 3463)
Regarding the one who commits suicide, Allah the Exalted said that My servant hastened before Me and did not show patience, otherwise I Myself would have given him death. This is in terms of the apparent situation; otherwise, it is evident that his death also occurred at its appointed time. He should have acted with patience and fortitude and entrusted his death to his Lord, but he acted hastily, even though Allah the Exalted had not informed him of the time of death. Therefore, he became deserving of the punishment mentioned in the hadith.
(2)
If he considered suicide to be permissible and lawful, then his punishment will be eternal.
It can also mean that Paradise will be forbidden for him until he enters Hellfire.
It may also mean that this is to be understood as a threat and stern warning, because Paradise is forbidden for a disbeliever, and the one who commits suicide does not leave the fold of Islam.
The aforementioned hadith also does not indicate his disbelief.
And Allah knows best.