Ibn Abbas was asked ahout Tayammum. He said: "When Allah mentioned Wudu in His Book, He said: "So wash your faces and your hands (forearms) up to the elbows." And He said about Tayammum: "And rub therewith your faces and hands" And He said: "And the male thief and the female thief; cut off their hands." So the Sunnah for cutting is the two hands. So it is only the face and the hands, meaning, Tayammum."  

فِي كِتَابِهِ حِينَ ذَكَرَ الْوُضُوءَ (فَاغْسِلُوا وُجُوهَكُمْ وَأَيْدِيَكُمْ إلى المَرَافِقِ) وَقَالَ في التَّيَمُّمِ (فَامْسَحُوا بِوُجُوهِكُمْ وَأَيْدِيكُمْ) وَقَالَ (وَالسَّارِقُ وَالسَّارِقَةُ فَاقْطَعُوا أَيْدِيِهْمَا) فَكَانَتِ السُّنَّةُ في القَطْعِ الكَفَّينِ إِنَّمَا هُوَ الوَجْهُ وَالكَفَّانِ يَعْنِي التَّيَمُّمَ