Prayer: Praying in the Clothing of the Opposite Gender
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 832
It is not unlawful for a man to wear a woman's clothing, nor for a woman to wear a man’s clothing, and performing prayers with such clothing does not invalidate the prayer. However, based on obligatory precaution, it is not permitted for a man to appear in the form of a woman, and similarly vice versa.