Messenger of Allah (ﷺ) said, "Any slave whom Allah makes him in charge of subjects and he dies while he is not sincere to them, Allah will make Jannah unlawful for him."

[Al-Bukhari and Muslim].

Another narration is: Allah's Messenger (ﷺ) said, "He who does not look after his subjects with goodwill and sincerity, will be deprived of the fragrance of Jannah."

A narration in Muslim is: Messenger of Allah (ﷺ) said, "A ruler who, having control over the affairs of the Muslims, does not strive diligently for their betterment and does not serve them sincerely, will not enter Jannah with them."