Musnad Ahmad 30:211

Sufyan narrated to us, from Abu al-Zinad, from al-A’raj, from Abu Hurayrah, from the Prophet (peace and blessings of Allah be upon him): "The most despicable name in the sight of Allah on the Day of Resurrection is a man who calls himself the King of Kings." Abdullah said: My father said: I asked Abu ‘Amr al-Shaybani about the "most despicable" (akhna’) name in the sight of Allah, and he said: "The most lowly name in the sight of Allah."