Is the warning in the hadith: "Any man to whom Allah the Almighty has given knowledge, and he conceals it, Allah the Almighty will bridle him on the Day of Resurrection with a bridle of fire" restricted to concealment after being asked, or does it include everyone to whom Allah has given knowledge and he conceals it?

The warning mentioned in the Hadith (definition) is not exclusive to someone who was asked about knowledge and concealed it. Rather, it also includes concealing the clarification of a ruling on an issue in which people err, and abandoning the denunciation of evil. The sin intensifies if the concealment is for the purpose of condoning the perpetrator of evil. Islamic law has tasked the scholar with teaching what he knows. Allah Almighty says: "Indeed, those who conceal what We sent down of clear proofs and guidance after We made it clear for the people in the Scripture – those are cursed by Allah and cursed by the cursers." The Prophet (peace be upon him) said: "Convey from me, even if it is a single verse." This is a severe warning, especially if the concealment is for a corrupt purpose, such as facilitating matters for oppressors, seeking worldly gain, or being miserly with knowledge.