Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates that the Prophet (peace and blessings be upon him) performed ablution, and then he narrated the long hadith. He says: Then he (peace and blessings be upon him) took some water and wiped his head with it, then wiped the inside of his ears with his middle fingers and the back of his ears with his thumbs. Hasan.
(b) Our companions say: It is as though he (peace and blessings be upon him) used to keep two fingers of each hand aside, and when he had finished wiping his head, he wiped his ears with them.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 315