It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: If a person is asked about any matter of knowledge and he conceals it without any valid reason, then on the Day of Resurrection a bridle of fire will be put in his mouth.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 7943
Hadith Gradingحکم دارالسلام:حديث صحيح، وهذا إسناد ضعيف لتدليس الحجاج، لكنه متابع.