prayer is a form of worship that God has commanded multiple times in the Holy Quran, promising response and impact in return. The question is, how is the effect of prayer based on philosophical foundations? In the present study, this question will be answered with a descriptive-analytical method and based on the doctrine of Divine Unity in Actions (Tawhid Af'ali), and the Principles of the three main schools of Islamic philosophy (Peripatetic philosophy, Illuminationist philosophy, Transcendent theosophy) will be explained and analyzed. The findings of the study indicate that Muslim philosophers emphasize the effect of prayer as one of the true causes of the system of existence, and although there is a difference in the how of the causality of prayer among the three mentioned schools, at the same time, by evaluating and comparing these three bases, the conclusion is reached that The soul, as a result of prayer, becomes prepared to receive the grace of the divine, so that God, who is the real cause, acceptance the request of the person praying. Therefore, the impact and causality of prayer, based on the worldview of all three schools of Islamic philosophy, ultimately lead to the god.