From Sahih Muslim (Hadith 5611):
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: Muslim 5611