Is it permissible for one who omits an essential act of prayer to lead anyone?
Chapter on Imamate and Congregational Prayer
Al-Mughni
Book of Prayer
Primary text
It is not permissible for one who omits an essential act (rukn) of the actions of prayer, such as one lying down or one incapable of bowing and prostrating, to lead anyone. This is the position held by Abu Hanifa and Malik. The evidence is that such a person has neglected a fundamental pillar that is not waived even in voluntary prayer, thus preventing those capable of performing it from following him, analogous to a reader leading an illiterate person. The right to stand is confirmed because it is waived in voluntary prayer and by the status of those following someone incapable. Furthermore, the Prophet, peace be upon him, commanded those praying behind one sitting to also sit, and there is no disagreement that one praying behind one lying down does not lie down.
Supporting text
Al-Shafi'i permits this, arguing that the act performed due to an ailment, which is permissible due to sickness, does not alter the ruling regarding leading the congregation, similar to one sitting leading those standing. However, the ruling concerning standing is confirmed by its omission in voluntary prayer and by the state of those following the incapable person.