It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that he said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The most detestable name in the sight of Allah is that a person calls himself 'Malik al-Amlak' (the King of Kings)."
Hadith Referenceالادب المفرد / كتاب الأسماء / 817
Hadith Gradingالألبانی:صحيح
Hadith Takhrij«صحيح : أخرجه البخاري ، كتاب الأدب : 6205 و مسلم : 2143 و أبوداؤد : 4961 و الترمذي : 2837»
Explanation & Benefits
Shaykh Maulana Usman Muneeb
Benefits and Issues: Magnificence (kibriya) is befitting only to Allah Ta'ala; therefore, any name that expresses magnificence is impermissible, such as "Shahanshah" (King of Kings), "Abul-Hakam" (Father of Judgment), etc. This is because the true Shahanshah is Allah Ta'ala Himself, and He is the greatest of all who judge and decide.
Source: Fadlullah al-Ahad: Urdu Commentary on al-Adab al-Mufrad, Page: 817