Sa'id bin Abi Maryam narrates from a man among the Companions of the Prophet (peace and blessings be upon him) regarding a man who wipes over his khuffs (leather socks), then it occurs to him and he takes them off; he said: He should wash his feet.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1370