What is the ruling on the followers' prayer if the Imam's prayer is invalidated due to an action that breaks the prayer?
Chapter on Praying with Impurity and Other Matters
Al-Mughni
Book of Prayer
Primary text
If the Imam's prayer is invalidated due to an action that breaks the prayer, and this action was done intentionally (amid), it invalidates the prayer of everyone. If the action was unintentional (without intent, 'an ghayr 'amd), the followers' prayers remain valid. Imam Ahmad ruled concerning the Imam laughing during prayer that it invalidates the Imam's prayer but not the followers' prayers.
Supporting text
There are two narrations from Imam Ahmad regarding the Imam experiencing an impurity that breaks the prayer (sabq al-hadath). One narration suggests the followers' prayer is invalidated because the Imam's action ruined his prayer, similar to omitting a condition, citing the report where 'Umar performed Maghrib without audible recitation, and when informed, he repeated the prayer along with the congregation. The sound opinion is to the contrary, as demonstrated when 'Umar, upon being wounded during prayer, directed Abd al-Rahman ibn Awf to lead them to completion; if their prayer had been invalidated, they would have been obliged to restart, and the analogy to omitting a condition is invalid because a condition is more firmly established, evidenced by it not being excused due to forgetfulness, unlike a mere invalidating action.