Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Any servant to whom Allah Almighty has granted knowledge and who conceals it — when he appears before Allah Almighty on the Day of Resurrection, he will have been bridled with a bridle made of fire."
Al-Tabarani recorded it in this way in al-Mu'jam al-Awsat, while in al-Mu'jam al-Kabir he recorded these words: "Whoever is asked about some matter of knowledge and conceals it will be bridled with a bridle made of fire on the Day of Resurrection." The chain of al-Mu'jam al-Awsat contains a narrator, al-Nadr bin Sa'id, whom al-Uqayli declared da'if (weak), while the chain of al-Mu'jam al-Kabir contains a narrator, Sawwar bin Mus'ab, and he is matruk (abandoned).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب العلم / 744
Hadith Takhrij«اخرجه الامام الطبراني فى معجمه الكبير 10197 ، 10089 اخرجه الامام الطبراني فى معجمه الاوسط 5540 ، أخرجه المعجم الكبير للطبراني برقم: 10089، 11310، وأخرجه المعجم الأوسط للطبراني برقم: 5023، 5536»