madinahimissA Hadeeth must meet the following five criteria in order to be accepted in Islamic law as a source of legal ordinance:

1. Continuity of the chain of transmitters (ittisal assanad):

This chain of transmitters has to be unbroken in order for the Hadeeth to be acceptable. That is, none of the transmitters must be missing from the chain of narrators.

Furthermore, each transmitter must also have heard the Hadeeth in question directly from the transmitter before him. Knowledge of this is verified with the help of the biographical sciences of the science of Hadith.

2. The integrity ('adaalah) of the transmitters:

The integrity of the transmitters is established in terms of their outward observance of Islaam. In other words, it is ascertained that they practice what is required of them by Islaam and they are not known to engage in the doing of things which are forbidden. Again this precondition is verified through the biographical sciences of Hadeeth.

3. Soundness of memory of the transmitters:

It must be verified through the biographical sciences of Hadeeth that each transmitter has a sound memory or that his books were accurate and that he only transmitted directly from his books.

4. Conformity of the Hadeeth:

It is important that the Hadeeth conform with similar Hadiths on the same topics which are stronger than it. This conformity should be both in the chain of transmitters and the text. Non-conformity in the chain of transmitters for example, might be if one of the transmitters in the chain is different than in a stronger version of the same Hadith. Non-conformity in text would imply divergence in the meaning of this Hadeeth with one which is stronger.

5. The absence of defects ('illah) in the Hadeeth:

A defect ('illah) in Hadeeth is defined as a hidden defect in the Hadeeth which takes away from its authenticity. A Hadeeth which has such a defect is one which appears to be free from defect at first while after investigation it is discovered that it has a certain defect which would not be apparent without investigation. The defect can be in the chain of transmitters or in text or both.