Purity: Distance from the Corpse During Prayer
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 588:
The person performing the prayer must not be far away from the corpse. However, there is no problem in him being far away if the prayer is performed in congregation and the rows are connected to one another.
-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)