Purity: Movement of the Hand During Wiping

Practical Laws of Islam as per the teachings of Ayatullah Sistani

Ruling 254

With regard to the wiping of the head and feet, one must draw his hand over them; therefore, if one keeps his hand still and draws his head or foot along it, the wiping is invalid. However, there is no problem if the head or foot moves slightly when one draws his hand over them.

-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)