Surah An-Nisa — Ayah 93 (4:93)
وَمَن يَقۡتُلۡ مُؤۡمِنٗا مُّتَعَمِّدٗا فَجَزَآؤُهُۥ جَهَنَّمُ خَٰلِدٗا فِيهَا وَغَضِبَ ٱللَّهُ عَلَيۡهِ وَلَعَنَهُۥ وَأَعَدَّ لَهُۥ عَذَابًا عَظِيمٗا ٩٣
English translation (Saheeh International)
But whoever kills a believer intentionally - his recompense is Hell, wherein he will abide eternally, and Allāh has become angry with him and has cursed him and has prepared for him a great punishment.
Brief commentary
If anyone kills a believer, deliberately intending to do so, his recompense will be Hell to live there eternally. Allah will be angry with him, distance him from His mercy, and will prepare for him a great punishment for committing such a serious crime. The belief of the Ahl as-Sunnah wa’l-Jamā’ah is that if the killer is a believing Muslim, he will not literally remain in Hell eternally; but he will be punished in it for a long period and will then be removed from there through Allah’s grace.