Is it permissible for a person praying individually (*munfarid*) to switch their intention mid-prayer to follow an Imam (*ma'mum*) when joining a congregation?
Chapter on Imamate and Congregational Prayer
Al-Mughni
Book of Prayer
Primary text
There are two scholarly narrations regarding switching intention from praying individually to following an Imam within the same prayer. The first narration permits this change, whether the individual is at the beginning of the prayer or has already completed one or more units (*rak'ah*). This permission is based on the principle that transferring oneself to follow the congregation is valid, similar to transferring one's intention to become the Imam. Furthermore, Imam Ahmad stated regarding a person who prayed two or three units intending Dhuhr alone, and then the congregation commenced the obligatory prayer: they should conclude their initial prayer and that prayer becomes voluntary (*tat'awwu'a*), and they should join the congregation.
Supporting text
The second narration prohibits this change, stating that transferring one's status to that of a follower without necessity is impermissible, contrasting this with transferring the intention to become the Imam, which is permitted due to necessity. Under this view, the individual must terminate their current prayer and restart it with the congregation. Imam Ahmad clarified that if a person enters the congregational prayer while already in their personal prayer and intends it to count, it is not sufficient unless the intention to pray with the Imam for the obligatory prayer is made at the very commencement of the obligatory prayer.