and for an amputee who has lost both hands, both feet, either one of them, or his nose; and for a man to lead one or more unrelated women when no man is present with them; or to lead people the majority of whom lawfully dislike him. It is valid for someone making up a missed prayer to follow a person performing it in its proper time, and the reverse likewise, but not for a person praying an obligatory prayer to follow someone engaged in a voluntary prayer, nor for one praying Ẓuhr to follow an imam praying a different obligatory prayer such as ʿAṣr. (1)

Section: The Positions of the Imam and the Congregants
It is recommended for two or more worshippers to stand behind the imam. It is also valid to stand on his right or on both his sides, but not solely on his left or in front of him. It is invalid for a single follower to stand alone behind the imam or behind a row—except that a woman following a man should stand behind him. When women lead other women, it is recommended that the acting imam stand in the same row with them.

Immediately behind the imam stand the men, then boys, then women, each rank arranged from the more meritorious to the next, just as in funeral prayer. If no one stands with the imam except a woman, someone known to have broken ablution or be physically impure, or a boy in an obligatory prayer, he is deemed to be praying alone.

Whoever finds an opening in a row must enter it; otherwise he should stand on the imam’s right. If that is impossible, he should signal someone to come and stand with him.

If a person completes an entire rakʿah by himself, his prayer is invalid. However, if he bows alone and then joins the row—or another person joins him—before the imam prostrates, the prayer is valid.

Section: Following the Imam
It is valid for a follower in the same mosque to pray behind the imam without restriction, provided he can hear the takbīr. The same ruling applies to someone outside the mosque, provided he can see the imam or those praying behind the imam.