Good Manners and Form (Al-Adab)
Ṣaḥīḥ al-Bukhārī 6205
أَخْنَى الأَسْمَاءِ يَوْمَ الْقِيَامَةِ عِنْدَ اللَّهِ رَجُلٌ تَسَمَّى مَلِكَ الأَمْلاَكِ
akhnā al-asmāʾi yawma al-qiyāmah ʿinda-Llāh rajulun tasammā malika al-amlāki
Transliteration generated from the Arabic vowel marks
The full narration
Narrated Abu Huraira:Allah's Messenger (ﷺ) said, "The most awful name in Allah's sight on the Day of Resurrection, will be (that of) a man calling himself Malik Al-Amlak (the king of kings)
Source
Ṣaḥīḥ al-Bukhārī · 6205
Ṣaḥīḥ