Humayd says: Sayyiduna Anas (may Allah be pleased with him) performed ablution while we were with him. He wiped the outer and inner parts of his ears, and he saw us looking at him intently, so he said: Sayyiduna Ibn Mas'ud (may Allah be pleased with him) used to command us to do this.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 303