One of the controversial issues of Arabic language is Al-prefixed to a participle which acts like a relative pronoun. In this regard, participles include اسم فاعل (the active participle), اسم مفعول (the passive participle), الصفة المشبهة (another participle in Arabic), which al attached to them. The grammarians have different approaches to this issue whether al is considered a definite word or it is regarded as an alphabetical Mosoul such as Ann (أن) or Ma (ما). Often, grammarians believe that when Al attaches to اسم فاعل (the active participle) and اسم مفعول (the passive participle), it will be like الذی (Allazi) and its equivalents. In contrast, there are some scholars argue that even when it comes upon اسم فاعل (the active participle) and اسم مفعول (the passive participle), it will maintain its original state and is merely a definite article. Some also believe that Al will be حرف موصول (relative letter) like ما (Ma) and أن (An) and not اسم موصول (relative pronoun). Few grammarians also believe that Al that comes upon اسم فاعل (the active participle) and اسم مفعول (the passive participle) will be موصول relative pronoun which is derived from الذی (Allazi). The aim of this study is to find a clear response for this important issue in the light of analysis of controversial views based on a logical approach called exceptional separated analogy (قیاس استثنائی انفصالی). One of the most important findings of this study is that Al is included in the names فاعل (the active participle), اسم مفعول (the passive participle) is اسم موصول (relative pronoun) unlike those who thought it is a letter (حرف).