Imam Ibn Katheer wrote in Al-Bidaya wan-Nihaya:
When (The oppressive Mongol Muslim ruler), Sultan Qazaan asked Ibn Taymiyyah to supplicate for him then he (Ibn Taymiyyah) said:
“O Allah if this slave of yours is praiseworthy and fights to make your word supreme and that you should be followed by everyone then help him and give him strength and make him a leader of the countries and people.
But If he is doing this to show off his reputation, and taking from this world so that he can be famous, and to humiliate Islam and its people then take him, destroy him, and cut his roots.”
Sultan Qazaan said ameen to his prayers and raised his hands.
Source:
Life of Ibn Taymiyyah in alBidaya wal Nihaya
Saheehus-Seerah 