Purity: Obligation to Wipe the Feet
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 251
After wiping the head, one must wipe the upper part of the feet with the wetness of the wuḍūʾ water that has remained on his hands. The area that must be wiped is from the tip of one of the toes to the ankle; and based on obligatory precaution, wiping the feet up to the raised part in the middle of the foot [before the ankle] will not suffice. And the recommended precaution is that one should wipe the right foot with the right hand and the left foot with the left hand.
-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)