Musannaf Ibn Abi Shayba 1:1905

Hushaym narrated to us, from Ibn Abi Layla, from his brother Isa ibn Abd al-Rahman, from his father, who said: I saw Umar ibn al-Khattab urinate, then he performed ablution and wiped over his leather socks. He said: To the extent that I was looking at the trace of his fingers upon his leather socks.