Whoever is asked about knowledge and conceals it will be brought on the Day of Resurrection bridled with a bridle of fire

It is narrated from Ibn Jurayj that Imam al-A'mash came to Ata (bin Abi Rabah) and asked him about a hadith, and he narrated it to him. We said to Ata: "You narrate this hadith to him even though he is an Iraqi?" (At that time there was rivalry between the scholars of Makkah and Iraq.) Ata said: "Because I heard Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrate this hadith from the Messenger of Allah (peace and blessings be upon him): 'Whoever is asked about some knowledge (which people need) and conceals it, will be brought on the Day of Resurrection bridled with a bridle of fire.'"
This is a hadith that is widely known among people through many different chains, and this chain is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it.

I discussed this chapter with our Shaykh Abu Ali al-Hafiz and asked: "Is any of these chains from Ata authentic?" He said: "No." I asked: "Why?" He said: "Because Ata did not hear it from Sayyiduna Abu Hurayrah (may Allah be pleased with him)." So we received this hadith in which an unnamed man stands between Ata and Abu Hurayrah, that the Messenger of Allah (peace and blessings be upon him) said: "Whoever is asked about knowledge and conceals it, Allah will bridle him on the Day of Resurrection with a bridle of fire." I said to him: "Azhar bin Marwan or your Shaykh Ibn Ahmad al-Wasiti made an error in this, and an error from either of them is not unlikely."

It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Whoever is asked about knowledge that he has and conceals it, Allah Almighty will bridle him with a bridle of fire on the Day of Resurrection."
When I presented this chain, Abu Ali al-Hafiz approved of it and accepted my point. Then, when I gathered all the narrations of this chapter, I found a group who mentioned Ata's direct hearing from Sayyiduna Abu Hurayrah (may Allah be pleased with him) in it. We also found this hadith from Abdullah bin Amr (may Allah be pleased with them both) with an authentic chain that has no dust upon it.

It is narrated from Sayyiduna Abdullah bin Amr bin al-As (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever conceals knowledge, Allah will bridle him on the Day of Resurrection with a bridle of fire."
This is an authentic chain from the narration of the Egyptians, on the condition of the two Shaykhs (Bukhari and Muslim), and there is no hidden defect ('illah) in it. In this chapter there is also a group of Companions besides Abu Hurayrah.

It is narrated from Amir al-Sha'bi that Qarazah bin Ka'b said: We set out intending to go to Iraq, and Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) walked with us as far as Sirar. He performed ablution and then said: "Do you know why I walked with you?" They said: "Yes, we are the Companions of the Messenger of Allah (peace and blessings be upon him), so you walked with us." He said: "You are going to the people of a town where the sound of the Qur'an resounds like the humming of bees. So do not begin with hadiths as soon as you reach them, lest you distract them. Keep the Qur'an pure, and narrate little (hadith) from the Messenger of Allah (peace and blessings be upon him). Go, and I am your partner (in this decision)." When Qarazah arrived there, the people said: "Narrate hadith to us." He said: "Ibn al-Khattab (Umar, may Allah be pleased with him) has forbidden us."
This is a hadith with an authentic chain that has several routes which are gathered together. Qarazah bin Ka'b al-Ansari is a Companion who heard from the Messenger of Allah (peace and blessings be upon him), and our condition regarding the Companions is that we do not pass over them, while the two Shaykhs used the rest of its narrators as evidence.