Abu Hurairah (May Allah be pleased with him) reported:
The Messenger of Allah(ﷺ) said, "He who does not acquire knowledge with the sole intention of seeking the Pleasure of Allah but for worldly gain, will not smell the fragrance of Jannah on the Day of Resurrection."[Abu Dawud].
App reference: Book 13, Hadith 16
Arabic/English book reference: Book 13, Hadith 1391