Encyclopedia of Prophetic Hadiths

The Messenger of Allah (may Allah's peace and blessings be upon him) was asked about the foremost deed that leads people to Paradise, and he replied: "Fear of Allah and good character." Then, he was asked about the things that most lead people to Hellfire, and he said: "The tongue and the private parts."

"Whoever acquires knowledge that should be pursued for the sake of Allah Almighty for the sole purpose of securing worldly gains shall not smell the ‘Arf of Paradise on the Day of Judgment." i.e., its fragrance.