Prayer: Praying in a Secluded Place with a Non-Mahram
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 875
It is unlawful for a man and a woman who are not maḥram[1] to be in a secluded place together if there is a probability of a sin taking place. And the recommended precaution is that [in such a situation] they should not perform prayers there.
-Ayatullah Sistani, Practical Laws of Islam, Prayer (Salah)
1
A maḥram is a person one is never permitted to marry on account of being related to them in a particular way, such as being their parent or sibling.