The Prophet ﷺ said, "Whoever conceals knowledge that he possesses will come on the Day of Resurrection bridled with a bridle of fire."
حدثنا محمد بن يزيد أخبرنا الحجاج عن عطاء
عن النبي ﷺ قال من كتم علما يعلمه جاء يوم القيامة ملجما بلجام من نار
Its chain of transmission is sahih. Ibn Majah narrated it 1/97 no. 265 in the Introduction, and Tabarani in Al-Kabir 5/11 no. 10845, and Haythami said 1/163, its narrators are trustworthy, and Ibn Hibban 1/55 no. 95, and Hakim 1/102 graded it sahih, and Dhahabi agreed with him.