Riyad us Saliheen: Hadith 1619

The Messenger of Allah (ﷺ) said, "A person who acquires (religious) knowledge, which is (normally) acquired to gain the Pleasure of Allah, (for the sole reason) to secure worldly comforts will not even smell the fragrance of Jannah on the Day of Resurrection (i.e., will not enter Jannah)."

[Abu Dawud].