Wiping over both feet will be equivalent to washing them, as long as the feet are uncovered and not covered by leather socks, and if he removes the leather socks, even if he wore them in a state of purity, then when he washes both feet, he will fulfill the obligation and will not be sinful, except if he abandons wiping out of disregard for the Sunnah of the Prophet (peace be upon him), then he will be sinful.

Sayyiduna Ali (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) granted us permission to wipe over the leather socks: for the traveler, three days and nights, and for the resident, one day and night.