Studying the phrase of

Hadith, as one of the important resources for attaining Islamic Law and knowledge, has been based on documents. Hence one way to understand that it is related to infallible persons (Masoumin) and it is authorized is to study its documents and grounds; which is a study different from Hadith studies. Learned men in Rijal science have used some of the phrases and the terms which are not clear in their meanings. However it is necessary to make the meanings of these terms clear so that the studying of Hadith documents and authorities take a better situation. Among these terms and phrases is ""Laisa be zalik al-Qavi" (That is not a strong one). The author tries in the paper to ascertain the status and the grade of this term in regard of its weakness and strength of the narrators and finally to distinguish its exact signification.