It was narrated from Ibn 'Umar that:
He saw Sa'd bin Malik wiping over his leather socks and said: "Is it you doing this?" They both went to 'Umar and Sa'd said to 'Umar: "Give my brother's son a verdict regarding wiping over leather socks." 'Umar said: "We used to wipe over our leather socks when we were with the Messenger of Allah and we do not see anything wrong with that." Ibn 'Umar said: "Even if that is after one has defecated?" He said: "Yes."
English reference: Vol. 1, Book 1, Hadith 546
Arabic reference: Book 1, Hadith 589