Musannaf Ibn Abi Shayba 1:687

Abu Khalid al-Ahmar narrated to us, from Uthman ibn al-Aswad, from Ikrimah ibn Khalid, who said: When Umar was in a state of major ritual impurity (janabah), he would wash his private parts, then perform his ablution (wudu) for prayer, then pour water over himself.