Background and Aims: The qadha of fasting and the qadha of the parents' prayers are important issues that need to be explained and analyzed. The purpose of this article is to examine the reasons and foundations of the obligation of fasting and prayer performed by parents on the eldest male child.
Materials and Methods: This article is descriptive and analytical. Materials and data are also qualitative and data collection was used in collecting materials and data.
Ethical Considerations: In this article, the originality of the texts, honesty and trustworthiness are observed.
Findings: In Imamiyeh jurisprudence, performing the out of date of prayer and prayer for the dead is one of the most important issues, and most of the jurists believe that the prayer and prayer of deceased parents is the responsibility of the eldest son. In this research, the purpose of this study is to explain the basics of this theory and to state the reasons of the opponents of this theory. The proponents of this theory have cited narrative reasons and other reasons such as the popular consensus and sayings; and against the opponents of this opinion, they have cited the Qur'anic verses and principles such as the principle of innocence and the rule of direct assignment of the matter to the obligee.
Conclusion: After examining the arguments of the opponents and those in favor, the chosen opinion is that the obligation of qadha is the responsibility of all the children, and they, as heirs, must perform qadha of the deceased or their parents in proportion to their share of the inheritance of prayers and fasting. And since there is no reason for the necessity of the mother's out of date, this obligation will only be the father's out of date.