Is it sufficient, when wiping the head for ablution, to wipe from the front to the back without returning, or is it necessary to return from the back to the front for the ablution to be valid? Do all schools of thought stipulate this? And how is it possible to return with the same water from the back to the front and wipe the ears with it, even though the water becomes used? And does Sheikh Ibn Baz’s statement that the purpose of wiping back and forth is to wipe all parts of the hair mean that the ablution of one who only wipes the front is invalid?

It is obligatory to wipe the head once. The Sunnah is to start from the front of the head and then move the hands to the nape. Returning the hands to the front is recommended but not obligatory. Therefore, the ablution is valid for one who moved their hands to the back without bringing them forward again. The water remaining after the first wipe is pure. Moving the hands back and forth in wiping the head is considered a single wipe. As for the statement that water used in an obligatory purification becomes pure, there is a difference of opinion among jurists on this matter.