(4) باب تَحْرِيمِ التَّسَمِّي بِمَلِكِ الأَمْلاَكِ وَبِمَلِكِ الْمُلُوكِ
Abu Huraira reported from Allah's Messenger (ﷺ) so many ahadith and one of them was this that Allah's Messenger (ﷺ) said:
The most wretched person in the sight of Allah on the Day of Resurrection and the worst person and target of His wrath would of the person who is called Malik al-Amlak (the King of Kings) for there is no king but Allah.
Reference: Sahih Muslim 2143 b
In-book reference: Book 38, Hadith 26
USC-MSA web (English) reference(deprecated numbering scheme): Book 25, Hadith 5339