The Messenger of Allah ﷺ said, "Whoever conceals knowledge, Allah will bridle him on the Day of Resurrection with a bridle of fire."
أن رسول الله ﷺ قال: من كتم علما ألجمه الله يوم القيامة بلجام من نار.
Ibn Hibban (96), Hakim (1021), and Bayhaqi in Madkhal (575) all narrated it via the route of Ibn Wahb, from Abdullah bin Ayyash bin Abbas, from his father, from Abu Abdul-Rahman Hubli, from Abdullah bin Amr, who related the hadith.Hakim said, "This is a sahih hadith among the hadiths of the Egyptians, meeting the standard of the two Shaykhs, and it has no defect."I say, it is not as he said, for Abdullah bin Ayyash bin Abbas was only included by Muslim, and there is disagreement about him. Nasai declared him daif. Abu Hatim said, "He is not firm, he is truthful." Ibn Hibban mentioned him in Thiqat (7/51). Ibn Hajar said in Taqrib, "Truthful but prone to error, Muslim cited him among the corroborating witnesses."On this subject, there is also what was narrated from Abdullah bin Abbas, as a raised report, "Whoever is asked about knowledge and conceals it will come on the Day of Resurrection bridled with a bridle of fire, and whoever speaks about the Quran without knowledge will come on the Day of Resurrection bridled with a bridle of fire."Abu Yaala (2585) narrated it from Zuhayr, who said, Yunus bin Muhammad told us, Abu Awana told us, from Abdul-Ala, from Saeed bin Jubayr, from Ibn Abbas, who related it. Ibn Hajar cited it in Matalib Aliyah (3/115) through the channel of Abu Yaala and said, "Sahih."Haythami said in Majma (1/163), "Abu Yaala narrated it, and Tabarani in Kabir narrated it in abridged form regarding the part about the Quran, and the men of Abu Yaala's narration are the men of the sahih."Tirmidhi (2950) narrated it through another route, from Sufyan, from Abdul-Ala with his chain, giving the second part of the hadith, and he said, "Hasan sahih."I say, perhaps these scholars judged this hadith sahih because of its corroborating reports, for otherwise its chain contains Abdul-Ala, who is Ibn Amir Thalabi Kufi. He was declared daif by Ahmad, Abu Zura, Abu Hatim, Nasai, Ibn Adi, Ibn Main, Yahya bin Saeed, Abu Ali Karabisi, Aqeeli, Yaqub bin Sufyan, Ibn Saad, Daraqutni, and others.