Hadith: My servant hastened to bring about his demise; I have forbidden Paradise to him.

جُنْدُبُ بن عبد اللهِ البجلي رضي الله عنه قَالَ: قَالَ رَسُولُ اللَّهِ -صلى الله عليه وسلم -: «كان فيمن كان قبلكم رجل به جُرْحٌ فَجَزِعَ؛ فأخذ سكِّينا فحَزَّ بها يده، فما رَقَأَ الدم حتى مات، قال الله عز وجل : عبدي بَادَرَنِي بنفسه، حرمت عليه الجنة».
[صحيح] - [متفق عليه]

Jundub ibn ‘Abdullāh al-Bajali (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "Among those who were before you, there was a man who was injured. He was impatient so he took a knife and made a cut in his hand and bled to death. Allah, the Exalted, said: 'My servant hastened to bring about his demise; I have forbidden Paradise to him.'"
[Authentic hadith] - [Narrated by Bukhari & Muslim]

Explanation

The Prophet (may Allah's peace and blessings be upon him) told his companions about a man from the past nations who had an injury that caused him much pain. He lost hope in Allah's mercy and healing and did not bear the pain in hope for Allah's reward, because he had weak faith and certainty. Therefore, he took a knife, cut his hand, and bled to death. So, Allah, the Exalted, said (what means): My servant did not wait for my mercy and healing, and could not endure the affliction that I tested him with, so he committed the sinful crime of taking his own life ahead of the time I appointed for him. Therefore, I made Paradise forbidden for him. Anyone who is forbidden Paradise will end up in Hellfire. There is no doubt that the action of that man was already known to Allah, the Exalted, as part of His prior knowledge, His will, and His decree.