Safwan bin Muhriz al-Mazini (may Allah have mercy on him) relates that Sayyiduna Jundub (may Allah be pleased with him) passed by some people who were reciting the Qur'an, and he said: "Do not let these people deceive you; today they are reciting the Qur'an, and tomorrow they will be fighting one another with swords." Then he said: "Bring me some of the reciters of the Qur'an, and let them be elders." So I brought Nafi' bin al-Azraq, and I also brought Mirdas Abu Bilal, along with six or eight others with them. When we entered upon Jundub (may Allah be pleased with him), he said: I heard the Messenger of Allah (peace and blessings be upon him) say: "The example of one who teaches people good and forgets himself is like the lamp that gives light to people and burns itself. Whoever shows off his knowledge to people, Allah will expose his showing off on the Day of Resurrection, and whoever publicises his deeds among people, Allah will publicise his disgrace." "And know that when one of you dies, the first part of him to rot is his belly, so do not let anything but what is pure enter your belly. And whoever among you is able to ensure that not even a palmful of blood comes between him and Paradise, let him do so."
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 1672