Yahya related to me from Malik from Abdullah ibn Dinar that hehad seen Abdullah ibn Umar with a man praying at his side. When theman sat in the fourth raka, heput both feet to one side and crossedthem. When Abdullah finished, he disapproved of that to him, and theman protested, "But you do the same." Abdullah ibn Umar said, "I amill."
App reference: Book 3, Hadith 52
USC-MSA web (English) reference: Book 3, Hadith 52
Arabic reference: Book 3, Hadith 199