What is the ruling if a traveler praying behind a resident intends to shorten the prayer?
Chapter on the Traveler's Prayer
Al-Mughni
Book of Prayer
Primary text
If a traveler intends to complete the prayer (intending full performance) or prays behind a resident, the prayer becomes obligatory as complete (four rak'ahs). If the traveler then invalidates that prayer (e.g., by breaking purity) and intends to repeat it, the repetition is also obligatory as complete because the initial engagement in the prayer behind the resident necessitated its completion. This is the position of Al-Shafi'i.
Supporting text
Al-Thawri and Abu Hanifa maintain that if the Imam's prayer is invalidated, the traveler returns to his original status, meaning he may then shorten his subsequent prayer. The opposing view holds that since the prayer became obligatory in its complete form upon commencing it behind the resident, it cannot be shortened subsequently, even upon repetition.