The difference between al-Hadith as-Sahih, al-Hasan and al-Daief.

A sound Hadith: Is that which has a connected chain of reporters characterized by being just and precise without irregularity or weakness in the chain.
Just means: One who has piety, faith, and obedience to Allah's Commandments and avoids prohibited activities.
Precise means: That the reporter should be known to possess the necessary accuracy in reporting.
Connected Chain means: There is no interruption in narration chain.
Irregularity referred to in the definition of the sound Hadith arises when a trustworthy reporter is contracted by another who is more trustworthy.
Weakness: arises when there is suspicion either in the text of the Hadith or its reporters, hidden or unhidden.
A good Hadith: A Hadith narrated by reliable chain, but one of the narrators of which does not approach in moral excellence those of the sound Hadith.
A weak Hadith: An inaccurate narration which does not qualify to be either sound or good, and hence cannot be used as a basis of an Islamic opinion.
Allah knows best.
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