Indeed the topic of the Fiqh of Du'aa is a topic which is vast and of the utmost importance; because it is from having comprehension of the religion. It is affirmed within the authentic Hadeeth from the Prophet (sallallahu 'alayhi wa sallam) that he said: "He for whom Allaah wants good, He gives him Fiqh (understanding/comprehension) in the religion." Therefore, Fiqh of Du'aa is Fiqh in the religion. Rather, it is Fiqh of a great aspect and the utmost importance in the religion of Allaah, the Majestic and High. What indicates this is the statement of Allaah, the Mighty and Majestic: So, call you (O Muhammad (sallallahu 'alayhi wa sallam) and the believers) upon (or invoke) Allaah making (your) religion pure for Him. [Soorah Ghafir 40:14]Here, He referred to Du'aa as being Deen (i.e. Religion). Likewise, he, the Blessed and High referred to Du'aa as being worship in several verses within the Qur'aan. Allaah, the Mighty and Majestic, has stated: And your Lord said: "Invoke Me, I will respond to your (invocation). Verily! Those who scorn My worship they will surely enter Hell in humiliation! [Soorah Ghafir 40:60]Here, He referred to Du'aa as worship.This meaning is affirmed within the Sunnah; within the Hadeeth of An-Nu'maan ibn Basheer from the Prophet (sallallahu 'alayhi wa sallam) that he said: "Ad-Du'aa is worship." Rather, It is affirmed within Al-Mustadrak by Al-Haakim and others, from the Hadeeth of Ibn 'Abbaas, may Allaah be pleased with him, in a Marfoo' form (that he said): "The best act of worship is Ad-Du'aa." Therefore, Fiqh in Du'aa is Fiqh in religion and Fiqh in the worship of Allaah the Majestic and High. So it is a beautiful act of worship and a great act of obedience; it is a magnificent means of nearness which Allaah loves from His slaves. The research in this subject is very broad, and its aspects are great and extensive. However, I ask Allaah, the Majestic and High, to facilitate for me to bring the pivotal points of this topic and review of some of its significant aspects