Do the Malikis stipulate rubbing the limb during all three washes for the ablution to be valid, or is it sufficient for them to rub it even once?

Rubbing is one of the obligatory acts of ablution (wudu') according to the Maliki school, and it is a condition for the validity of the ghusl (ritual bath). Rubbing should be performed during the first, second, and third washes.