Good Manners and Form (Al-Adab)
Ṣaḥīḥ al-Bukhārī 6206
أَخْنَعُ اسْمٍ عِنْدَ اللَّهِ ـ وَقَالَ سُفْيَانُ غَيْرَ مَرَّةٍ أَخْنَعُ الأَسْمَاءِ عِنْدَ اللَّهِ ـ رَجُلٌ تَسَمَّى بِمَلِكِ الأَمْلاَكِ
akhnaʿu āsmin ʿinda-Llāh waqāla sufyānu ghayra marratin akhnaʿu al-asmāʾi ʿinda-Llāh rajulun tasammā bimaliki al-amlāki
Transliteration generated from the Arabic vowel marks
The full narration
Narrated Abu Huraira:The Prophet (ﷺ) said, "The most awful (meanest) name in Allah's sight." Sufyan said more than once, "The most awful (meanest) name in Allah's sight is (that of) a man calling himself king of kings." Sufyan said, "Somebody else (i.e. other than Abu Az-Zinad, a sub-narrator) says: What is meant by 'The king of kings' is 'Shahan Shah
Source
Ṣaḥīḥ al-Bukhārī · 6206
Ṣaḥīḥ